The controls were weird for maybe 5 minutes, then they got pretty natural. Its a great game as is, just needs more campaigns.
Why are so many assholes play this game?
Because its free, and the swarm of people still trying to get the tf2 hat.
Played with a group of public people, and they killed me at the end of cargo elevator because I was getting a few extra kills for an acheivment from that near-infinite spawn at the end. I seriously wasn't doing it for more than 30 seconds, but they all opened fire on me anyway. I left.
Played with a group of public people, tried doing the same thing. Some guy starts flipping out on me over his mic for taking too long. I reply "Whats the matter, gotta go jack off in five minutes? give me a fucking break and let me get an extra 9 or 10 kills" When we got back to the lobby, I was kicked.
TRIED playing with a group of public people, a bunch of arrogant third-level promotion level 27s, who kept telling me all the weapons and items I used suck, and that I'm a "nub faggot" Might I say squad inventory coordination isnt terribly neccesary on NORMAL. I left.
Enough ranting about asshole player-bases.
tl;dr A large number of Alien Swarm players are angry little kids who wouldn't be able to afford the game, but have it anyway because its free.