Here's my impressions from my 6 hours or so of gameplay from yesterday. The game is really good.
I should note - I'm playing on "Give Me a Challenge." Maybe this is why I haven't noticed anything odd or out of the ordinary when facing AI. Maybe I'll stumble across something? I don't know. [shrug] Mye eyes will stay peeled.
The voice-acting, storytelling, and everything - it's all really-really good. Nothing has seemed or felt off in this game.
The graphics - well, they're not horrible and they're not spectacular, either. The characters models look great sometimes, sometimes not-so-much. Adam looks like a bad-ass, though. Sometimes, animations seem a little stiff - especially after playing something like AC: Brotherhood. On the other-hand - the details in the game environments and the art-design in the game-world are pretty good, though.
The gameplay has VASTLY improved. There's a cover system - and the game jumps to 3rd person when you do so. You can now cover behind things; move from cover-to-cover; pick-up portable objects [boxes] to use them as cover; and so forth. You get a headshot, expect points for being a "Marksmen." The first person shooting feels great.
You get even "Scholar" points for reading certain E-books and stuff in the game-world.
A breath of fresh-air, compared to Mass Effect games on the dialogue selection. Here's a game that finally gives us dialogue and it plays out EXACTLY like how you selected it. Not always, though - since he might say MORE than what your option was. This is fine, as it all stays on the same wavelength as the decision, though.
Like previous Deus Ex games, expect often - especially on main quests - multiple points of entry into an area. In most cases, you can stealth, shoot, hack, or mix-and-mash your way through an area.
Stealth attacks look nice. Whether it's a knock-out or a kill, it just looks sweet.

The Inventory is back to the grid-style from Deus Ex 1, PC gamers. If you liked that - you'll be happy w/ this decision to bring that back. I know that I sure am.
One question - are there any melee weapons in this game? I just...haven't ran into any...
EDIT:
GameSpy's Graphics Guide for Deus Ex: Human Revolution PC.