I own it and I have to say its very VERY annoying, I get a sniper bam bam bam... out of ammo... AHhrar!!! I've only played it with my friend and find it very stupid that you pretty much have to pick up every single ammo pack that drops. The co-op shield thing fails hard, and so does the co-op snipering.
Its good so far but its not as good as every one was saying it is.