MAG is not a fun game.
I was really excited when this game was coming out, and I picked it up the moment I bought my PS3. This was a big mistake.
The only thing that this game does well is the fact that it doesn't lag when you're playing with 256 people. Unfortunately, everything else about the game is lackluster.
Despite having 128 people to a team, everything about the game is boring. The objectives are boring, the weapons are boring, and there's very little actual skill involved in the actual gameplay.
Don't be fooled by the huge player count, the game is uninspired and uninteresting, and you should let it pass by. There are some better shooters on the PS3, like Resistance 2, so I suggest you get one of those.