You should read through some of the articles they have up at the site, especially the ones on the New Tech and the New Fighting Mechanic. One speaks to the level of detail the will be in the visuals, the AI, and the game control. The gets to environments, both visuals and control, this gets to the level of detail, is completely changes the AI relations mechanic, it allows the game to tailor to the player on the fly, etc., etc. Interesting stuff, which could be awfully epic if they can pull it off.

The new melee mechanic is pretty exciting as well. Bethesda is paying a lot of attention to making the feel of this game be more... visceral. Weighted swings, jostling, have to intentionally block, shield bashes, dual wielding, slow back pedal, and much more. One of the highlight sections, in this and other articles, focuses on just how much time they've spent on reworking magic. They always felt that magic didn't seem all that magical, or immense, and they wanted to fix that.

The switch to two-handed loads, allowing for spell combinations, and the necessity to specialize, will add some interesting gaming situations. The perk tree and the varying way you can use magic will be interesting. Their example features a basic fire spell loaded... you can use this spell in a few ways... a simple tap would be a fire bolt, holding down for a while would build a massive fireball, you could load the power into a ruin tied to a floor/wall that you can trigger (which I believe is what see in the trailer), or you can spray fire from you hand like a flame thrower. That is some interesting combinations for a Fire Spell.