I know that this has been discussed before but I'd like to give my perspective as someone who's never played a mage.
I'm level 60. I'm bored. I've beaten the ebony warrior on legendary and despite my best efforts the game is going the same way. I'd thought to beat 'Ebony-Bonce', as I call him by using deathbrand armour and dual-wielding my best swords, since I'd not done that before, but somehow it wasn't enough....
...so I decided to put my enchanting and alchemy skills to good use and learn magic! After all, I am the Arch-Mage of Winterhold. After a lot of premature deaths I got my skills up in destruction, restoration and illusion (so I could get 'silent casting', critical to my sneaky way of playing). I then double-enchanted my gear, stepped out of Heljarchin Hall and had fun.
OMG, it was fun. Spells in destruction and restoration cost nothing. Some of the stronger opponents managed to drop my health, but most didn't. I had Serana with me and for once, I wasn't feeling like a spare part, or jealous because she was killing the enemies and stopping me from levelling up. ..it was a ball. I even stepped up to 'master' difficulty but nothing changed.
Zap! Zap! Roast!! Singe! Sparkle!...marvellous.
I'd like to play a mage from the start, rather than taking it up when I had the toys to make it easier.
I'd certainly say that at this level (60-ish) Magika is most definitely not underpowered.
I am saying that I wish I'd played as a mage before.