Their handling of the demo was quite honestly, awful.
Since the full game was going to use a lobby system instead of matchmaking, the matchmaking system implemented was rushed. And as a result, it barely works on the 360 and is outright defunct on PC and PS3.
On top of that, they couldn't have picked an existing game mode worse for the game. I hate to agree with Tim Buckley of all people but the demo doesn't play to the strengths of Aliens vs Predator.
In Free For All, it is one man against everyone. Since this is the precise direction that Predators went in, it is only natural that they have an advantage over everyone else. And since the marines were designed to work in teams, they got the shaft. Big time.
If this was Team Deathmatch(Much better for this demo), Marines would work in groups and the Predator's overall lacking in ability to work in teams would get the better of them.(One predator vs one marine = Marine dead. Three Predators vs Three Marines = Predators dead)
The core gameplay is great. Wall crawling is better than ever. The graphics are sublime. Shooting mechanics work. Weapons are awesome(Predator Disc = Razor wind from Turok 2. Awesome!) and the full version will be tons of fun.