ARS: Aliens vs Predator may very well be a good game, but the demo doesn't do much to sell it.
The demo is multiplayer-only and only showcases one map and one game mode: deathmatch. The servers are public and trying to find a game is an exercise in frustration. In over two hours spent with the PlayStation 3 version of the demo (it's also available on the 360 and PC) I managed to play a scant three games. And one of those got disconnected. Ben had similar issues when trying to connect to the PC version.
Once you actually get in a game things run pretty smoothly, though deathmatch isn't really the best way to show off a game with three unique races to play as. Especially when you seem to be randomly assigned a race. After a brief loading screen displaying the controls for the game, you're tossed into the fray with no other guidance.