Just saying it's a game for the 360 exclusively, that's actually good.
Which counters boblaw's argument, that all the 360's games are going over to the PC. Although, I must admit, it's true that most of the games are indeed going over to the pc. Still, that doesn't mean everything is going.
Also, I would get both, but I cannot afford both. I like the gaming library more of the 360, but like the hardware of the ps3.