Yeah, the best way to answer these questions is to download both the single player and multiplayer demos. You'll be hooked, I tell you.
AVP2 is worth buying, BUT.... if you ask me, if you choose easy on the marine missions it is too easy, choose normal or hard. I love the story line and the action on it. You get to the scenery after the 2nd mission, you will get use to the body parts and screams. But, the very first mission right when you get seperated is freaky. I liked it a lot.
17th June 2002
The best part about the marine missions is the atmosphere. You're constantly spinning around, thinking you've heard something or seen something move on your motion tracker. There are areas where you don't encounter a single alien, but you still move incredibly cautiously through them.
The best part about the Predator missions is the feeling of power. You're the only guy in the area who can take on an Alien in hand-to-hand combat. Humans, when they actually see you, are generally scared of you (though, not to the degree they were in AVP 1). Get injured? You've got a mobile medpack right there. One drawback is that you find yourself sifting energy, using your medkit, then sifting energy again quite frequently in some areas, which can get repetitive. And the plasmacaster (the shoulder cannon) is just awesome, and sounds authentic.
The best part of being an Alien is that you are an Alien. Dubbed the 'ultimate killing machines', I think. You can walk on walls and ceilings, you can pounce into someone so hard they literally fall to pieces. You can scare people completely shitless, and then take a bite out of their head. And although the speed isn't as high as AVP1, you're still a fast little git. Nothing quite like hanging off the roof above someone and taking off his head without him even seeing you...
Multiplayer is pretty good. I usually host a game with a couple of simple rules; keep the abusive behaviour down, and no whining about what weapons people are using. So it's generally pretty fun to stalk real humans as the Predator. Quite amusing in dark levels to use the verbal taunt, then move, and watch them fire into an empty area while you sneak around back and stab them.
I've been playing it on-and-off since the very day it was released. I'd say it's worth 20 notes.