To the OP. my personal view is that magic is less fun than prior game due to not enough variety in spells an no spell making. But it is still fun and I have played several mages in Skyrim.

Conjuration plus illusion and destruction is a powerful combination on any difficulty level because conjuration and illusion are not affected by the difficulty slider and those two alone make a very powerful combination an adding destruction can help clean up whatever survives your illusion and conjuration.

I like to hit bandits with fury an then start raisin them with necromancy until there is just your zombie left. In most situations you can get by with just conjuration and illusion.

You don't need alteration to be successful as a mage. Especially not a sneaky mage, since you should not be getting hit much. You have conjuration to creat meat shields and distractions and illusion (muffle an invisibility) to disappear if things get too rough. Plus, if you are not using mage armor perks, then you can wear armor with no penalty.

Good luck with your mage.

Okay, this is coming from a person who has traditionally despised role play in all of its forms, hates Princess Bride, hates Star Trek, is luke-warm about Star Wars, never played Final Fantasy, own and played Morrowind and Oblivion but hated them because role playing fantasy games were just "we-todd-did" in his opinion. I have always went back to my beloved Madden and Call Of Duty games because I loved them. With that being said, it gives you a bit of background about me and how I have always felt about RPG games. But Skyrim's magic (and overall game play) is awesome. Since I have no knowledge really about magic in the earlier ES games, I can only go with what I know in Skyrim - magic is great, if you know what you are doing.

None of this silly comparison to old ES games like "Oh, wah wah wah I miss spell creation....blah blah.....tina come get your ham...." type stuff. While it may have been good, your question is not "compare skyrim mage to other ES games magic". So, again, magic is great if you know how to use it. I always compare it to being a chess player (I LOVE chess). You must be tactical and not just go all "Leroy Jenkins" with destruction think its the end all be all. You need to plan and use support magic, walk into a bad guy's dwelling? Cast a flesh spell for armor, notice that bad guys have weakness to fire, conjure a couple of flame atronach, cast flame cloak, hit them with illusion spell, cast a flame rune, the duel equip fire bolt. Getting hurt? Cast a restoration spell. Running low on magica? Get your enchanting up and enchant some cost reduction gear or magic regen gear.

Magic is great, but it cannot be used like a first person shooter just going all willy nilly blasting things with destruction and thinking you'll be invincible. Have maybe a primary school (or two) that you use, then have a couple of other schools as backup.

You're recommending actually using SKILL to win fights? UNACCEPTABLE.

There are many ways to play as a mage in skyrim. You can use robes, you can use heavy or light armor. Its up to you, I've created at least 15 mages so I've played in many different ways.

Some of my favorite:

Rhuna Bloodmouth - Breton Necromancer who uses robes, alteration and electromancy. No weapons. Levels are all magica, health and stamina are still 100.

Khajit Vampire Lord (see signature below)

Ghostface Killa - Altmer Master Destruction mage (master of fire, shock and frost) who uses conjuration, alchemy for poisons and 100 fully perked one-handed wtih bound blade.

Red Fury - Dunmer of Telvanni descent who is master of all destruction elements, alteration and illusion. Uses robes only and enchanting.

Celene - Breton battlemage who used her conjuration skill to create Daedric armor and used enchanting and alchemy to make it legendary and duel enchanted. She primarily uses magic, but is also fully perked and can duel weild double enchanted Daedric swords.

These are just a few. I also have an Altmer mage who uses light armor. A pure mage Orc and a few more misc. characters. My suggestion is to play based on the personality of the character you create and go from there. That is what makes this game (compared to the other ES games) sooooo much MORE amazing.

I know, crazy huh? Hope I dont get flamed for suggesting it.

Look, basically Conjuration and Illusion are far more useful than Destruction. The game presents the illusion of strategy, but there isn't any, really. Any strategy you care to employ is simply a waste of time (primarily if the strategy takes into consideration Destruction spells, where the mana cost goes out of whack).

It gets even worse at higher diffiulties. Bethesda compensates for their horrible AI by turning enemies into tanks.

Conjuration and Illusion are the strongest magic schools, alteration is very useful, restoration is always useful, and destruction is good until you start playing on higher difficulties. You will need a big mana pool early on in the game in order to cast your spells, and later on when you have built up a good sized pool, you can start building up your health. Enchanting is also very valuable for a mage, as is alchemy. Destruction gets much better once you have enchanted items that reduce the magicka cost of its spells.

This is key right here^^

Then you can duel cast fireballs to your heart's content.

I have just started to play a mage "seriously" a couple of days ago, here's what I think of it:

Destruction is always my first choice when I encounter enemies, and due to the fact that many of the attackers in Skyrim are freeze-resistant, I would suggest using fire (aganist regular hostiles) and lightning ( against spell-casters).

Alteration is really important, since as mage I don't like wear armors at all. Seeing a mage with heavy helms and gauntlets is somehow weird to me. Mage armor is crucial for me when fighting, and of course oak/stone/iron/ebony flesh etc.

Restoration: no need to say anymore. It's life-saving.

Alchemist: also important because as a mage you are always short of money. In that way you make a lot of useful potions without having to pay, great way to save money. And another reason is I can make magic resist potions that would be of great benefit when fighting hostile mages.

Above are the main magic schools I use so far. Maybe I'd use more illusion when my level are higher (my level's 20 now). As for conjuration, I don't see the need, but it's personal choice.

Any decent spell costs way too much magicka, and basically all of your level-ups have to go toward it. If you want to have any fun, you have to deck out in the best robes possible that reduce magicka cost, but then the spells are next to ineffective. Destruction, anyway. And it's a pain in the ass to level up. Conjuration is one of the most useful and easiest to level up, next to Restoration. Only 2 schools I'll mess with if I want to be magic orientated. A Crusader is one of the best classes IMO.

That's weird. IMHO I can't play worriors because of the exact same reason, because it is much too repetitive, just hit then block then bash then hit and repeat. I do play thieves, mages, or a kind of rouge-worrier hybrid though.

Although I don't think of classes much as skyrim has no classes. That's also why I don't mind my Mage picking locks or sneaking, I don't consider him a thief Mage because he doesn't steal anything, but he is just being smart and finding the enemie before they find him and he knows how to pick locks because it is a skill he needs (but if there was a spell he wouldnt need it).

But to answer the op-
Illusion and conjuration are the two strongest skills, although the illusion tree requires almost full attention to be effective. I have manage to work illusion, destruction, conjuration, and restoration into my current Mage, and eventually he will begin using alteration although when I first started using it I had so many skills leveling that my enemies were out leveling me.

I recommend picking either illusion and/or conjuration, suplimenting it with some destruction and then picking either alteration or restoration. I like restoration because of the undead harming spells but it's your choice.

And alchemy is a must because you need restore magika potions and money

Conjuration for a Mage to me is more important than destruction. By summoning a minion, they draw the attention of the attacker in addition to dealing their own damage. And by doing so significantly increases the odds that you won't take damage, which lets face it, a Mage that wears only clothes/robes won't stand for very long if taking a physical beating.

I don't see a need for magic resist potions to fight other mages. That's what the magic resist perks and the wards are for.

I'm not criticizing by any means, just making a subjective rebuttal. Everyone has their way of playing and what works for you may not work for me and vice versa. That's what makes this game so great. So many ways to play.

Takes a great deal of Magicka for a lot of the spells. I usually distribute a few perks here and there for Destruction and Restoration, but usually only Apprentice Level spells. Which is to say, Firebolt and Fast Healing. Pretty Handy. I don't go for any higher level spells unless, on rare occasion, I wanna be a mage and deck out in spectacular gear that benefits and makes spellcasting helpful/enjoyable, not a chore. Other schools hold no interest me, except for maybe Conjuration. Enchanting is a 50/50. Usually Spend a Dragon Soul and reset it to get perk points back after I choose a set of armor/weapons I'm gonna be using for a while and enchant them.

I absolutely love Conjuration, especially Necromancy. When you go for that you can end up having awesome minions.

I don't really like Death Thralls though, so I don't use them, personally.

Destruction is cool aswell, but for me it is more of a backup skill instead.

Magic?
What magic!?
Oh, you mean fantasy themed guns, med packs and armor!
Yeah... plenty of those in this game.
/cynicism

Whit removal of spell making, most of magic got removed from magic in Skyrim.
I wouldn't mind it that much (or at all) if they implemented the mechanic where you can combine two different spells in each hand and get a new spell, but they didn't.

That's part of making a new game. If they kept all that then it would be Oblivion part 2. Developers can't keep making the same game with the same mechanics over and over. It's like when the developers over at Capcom decided to ditch the zombies for the RE series. I mean how many games can you make with zombies? This is the same concept here.
If people want the spell making, then play Oblivion.

Oh my God, yes. Silent casting + invisibility + 100 sneak + 100 one-handed + ebony dagger + enchantment + smithing improvement = lots of fun.

Every guard in every major city in Skyrim is dead in my current playthrough.

I tried going for a shield mage at first (light armor w/ magica regen enchantments, a light shield with shock resistance, and whatever destruction spell I wanted in my right hand), but I sort of abandoned that character in favor of the illusion thief that I have today.

I hope this is sarcasm.
Still, I did say that I would be happy if they implemented mechanic which allowed us to mix two different spells in each hand to get a new one just to keep some of the magic in magic.

My intention wasn't to offend you, and if I did I apologize. I was simply just saying that people are constantly comparing Skyrim to Oblivion. They're too totally different games with different mechanics and ways to level. That's all. But I agree, yes it would've been cool if they could've done that.

Naaah, all cool!
I was just wondering why would someone not want a cool mechanic which would make magic more magical (does not have to be limited to spell making or spell combining).
Still, maybe I didn't understand you properly (could always happen).

I have enchanting at 100 although I use so many skills that I just improved my magika and fortified all my skills ounce and I think it's the smarter decision.

Sure I could've had free destruction but then my conjuration and illusion and restoration would eat through my mana. But this way I have yet to run out.

I see your point and agree with you. As for conjuration, I think if I need someone to distract the enemy, I would pick a follower. The perks saved could be invested in schools like alchemy or restoration, or just any other skills you like. But as you said, there are unlimited ways to play, what makes TES a great game.