Ok, I had a run about and feel a little let down...
My biggest issue with the game is the matchmaking system, but it doesn't stop there. I think it would help to have a full group of people on your Steam friends list to invite into a group. I tried for ages to get a game on my own, but the moment I had two others in my group, it was almost instantaneous. So, in total, I've played maybe fifteen minutes
Found the Predator frustrating with no ranged weaponry - felt like I got seen every time I got within ten metres of an enemy - needs more subtlety, I guess. I was never one for sneaking about

The Marine was ok - the constant ping from the motion sensor was annoying - picking up a shotgun is possibly the most useless thing you can do - it's killing range is about 3 yards

Alien - no chance to try.
The level design of the map I played on was uninspiring and pretty basic. It felt too big with towering ceilings and not all that much in the way of cover. The graphics were not all that impressive either.
In all honesty, I'm struggling to think of anything which makes this game anything other than a future bargain bin purchase. That said, I have only had a short time to play - and I'll give it another go once I've got a few more Steam friends online and testing it out - who knows, my opinion might change - I'm ever optimistic.
If anyone wants to add me specifically to test out AvP, feel free:
http://steamcommunity.com/id/bewarethebear