I loved the first AvP for the reasons people already wrote here.
Marine campaign on hardest level in the middle of the night in a dark room with sound on max. Doesn't get any more scary than that.
Allien part was also awesome. When shot at using the Gatling from some distance you'd first hear the shots falling around you.. then die.. then hear the rotating sound.
Predator one was good in places(last 2 missions) not so good in others.
Multiplayer was cool.
Sadly Avp2 was a huge disappointment to me, specially the alien was really slow.
Hope it builds on the first game then.
Igiss says: Martin, you give them a finger, they bite off your arm.