I've seen the AI, and it's not badass like, it's somethin you've never seen before. It's definately good though. Best parts probably are the puppetmasters and the spectre's. Dave Matthews, the guy who gave the presentation, was really vocal about the AI, saying how an encounter with those monsters would never be exactly the same.
I did get to play the game a little, but can't really say how well the AI tries to create cover for itself, or if they really look for a watersource when they are on fire. An interesting piece of info was that they hired an ex-delta force guy, and made your opponents work like a delta-force team, clearing the rooms etc, but that way it was nearly impossible to win, so they had to turn it down a notch. Might be PR though, but it did make me wonder, maybe ultrahigh difficulty still has those settings.
As for the graphics, I've only played on xbox 360, but it looked good enough to me. I'm pretty sure most screenshots are taken on the xbox, so the PC version might look better. And, most of the time they don't do full debugging runs near the end, and then add all the lighting and what not. Me, I wouldn't worry to much about the graphics. It's also how the game uses it's graphics to create that horrorlike atmosphere, where Alma could creep up on you at every moment.