Installation was huge pain. You're required to install steam and run it to "unlock" certain game files -- I think by unlock, they mean download and even at Cable Modem speeds, downloading took 15-20 minutes (I'm sure the servers were being banged hard but that's no excuse)
That aside, I had some lag when I tried to run at 1024+Med/High settings. Going down to 800x fixed that.
Beautiful graphics, you can pickup and interact with everything. If it looks breakable, it is (if you apply the right force). You can throw lighter objects farther than heavy ones.
What is really amazing is the voice synch with the graphics. They have coded complex muscle movements to make the mouths look real and they move in outstanding synchronization to the words. Their eyes also follow you as you move about and their general movements are natural.
Will be playing all night tonight and let you know more then.