There are some features I'm really happy about: the detailed world, the more alien culture and setting (at least with respect to Oblivion). But those aren't new features. They're just a reinstatement of features that went missing for a bit.
There are also some features I'm really excited to hear more about, and I suspect I'll really enjoy: the new faction system, for example. But since those aren't confirmed...
As it stands, the new, confirmed feature I'm most happy about is probably the new leveling system. No classes, each skill contributes to leveling up, but higher valued skills make a greater contribution. I think this will make for much more fluid character customisation.
Well, either that or the ability to equip any item to either hand, in any combination. That opens up lots of interesting combat possibilities.
I'll have a hard time handling that. Or I could just put a healing spell on my left hand and use it to recover from the wounds that I couldn't block.
You could also put a shield spell in one hand and a weapon in the other...