I played a bit of the CO-OP mission this morning. Kinda felt bad for my partner as I was just running around to check out the graphics. When I did play more seriously, my partner had to keep reviving me because I kept getting shot while trying to taking out several enemies in a row with just melee. Also, I quit after 4-5 checkpoints.

Overall, it was fun but not ground breaking. The gunplay felt a little better than U1, mostly because the enemies didn't seem to soak up as many bullets before going down. Based on just what I played, it didn't seem like an OMG 10/10 experience but I'm guessing a good chunk of what people liked is in the campaign mode.
Technically, I was slightly disappointed. The image quality was superb and the framerate was stable. However, other than seemingly being more open, the game didn't seem to be doing much more graphically than something like RE4.