Duel wielding- you can now equip whatever you want to either hand, spell in your right, sword in your left, a spell in each hand, a sword and a board, etc.
Ambidextrous- you can now equip the sword or shield to either hand.
Sprinting- seems like it's there, would make stamina more useful of a stat.
Shouts- bad ass sounding(especially like the sound of the teleporting one.
skill perks- sounds like it could lead to some seriously specialized characters.
spells- seems you can now target, sustain(think flame thrower), place as traps, charge up. major upgrade in my opinion. spells were terrible in oblivion. these seem to be all doable in just one spell.
Enchant- the enchant skill makes a return(they removed it in oblivion but it was present in morrowind)
alchemy- moves outta the arcane set of skills and gets attached to the stealth/ assassin set.
Finishers- finishing moves are present now.
cooking- doesn't seem to have an associated skill with it but apparently it'll be in the game.
Improved ranged combat- sounds like they took a page from all those mods that upped the power of ranged combat in oblivion. archers will be feared now.
guilds- seems like they will be much better then in oblivion.
companions- generic compared to fallout 3 and new vegas, but apparently you'll be able to have multiple following you(makes sense with dragons( more targets means your less likely to be lunch)
things that have been removed.
no classes- seems like a step backwards at first but seems incredibly powerful after some thought. besides who ever played a default class? i usually created my own.
mysticism- no longer a skill, but the spells that normally would belong to it have been moved to other magic sets.
spellmaking- it's kinda up in the air, todd's not sure if it's coming back or not due to the way majicka now works in the game since each spell can be target, touch, area effect, etc all in one spell.
things that are still missing.
spears/pole arms- why? seems that with such large foes as dragons that a weapon with longer reach would fit really well into game play. plus imagine the finishers....
crossbows- actually im not sure if they are in it or not. seems to me they'd be a good fit, more powerful but slower for follow up shots.
thrown weapons- funny how they say they want you to play the way you want to yet don't give you the tools to do so... lol.
rideable horses- although one appears in the game play trailer, todd has said they are not sure if ride-able mounts will be in the game. if they end up like the horses in oblivion then i can live without them. (come on even twilight princess had horse back combat!!!)
un-knowns
levitate- will it come back?
mark and recall- very handy spells that were missing in oblivion.
intervention spells- nothing like a panic spell to save your butt.
horse stuff- if horses do make a come back will they finally have saddle bags to store extra loot and supplies in? will companions have horses? will there be horse armor?(lol)
un-armored- does this skill return?
un-armed- see above.^
armor skills- how will they work?
if i've missed anything, if i'm wrong about something then let me know and i'll fix it.
source for most of this is from the game informer site's skyrim hub.