I was able to play a few AvP demo matches and my response can be summarized in three letters: Meh.
Call of Duty 4 does modern weapon combat better.
Natural Selection, a Half-Life mod, does alien combat better. (Skulk > AvP alien.)
And I didn't play as Predator, so I can't post an informed opinion of the game's third faction.
Overall, the controls were awkward (initially leading me to believe that the game is based on Unreal Engine 3, which is incorrect; according to Wikipedia, the game uses a proprietary engine dubbed Asura), a lack of dedicated servers led to latency issues, the single level included in the demo was torn from the "real is brown" playbook, and the game is obviously designed for hardware more powerful than my notebook. It's not a bad game so much as one that I just didn't find myself enjoying.
It looks like I'm going to be playing Team Fortress 2 and Left 4 Dead 2 for a while; I'm just not feeling the last few new FPS games I've played.
But I will say this: Corp.fox rocks the AvP demo. In the one game we played together, he took the high score. If you've got a beefy computer, liked the AvP demo, and are looking for a challenge, keep an eye out for Corp.fox.