The third makes compromises in certain areas- you can only carry two weapons now (some capable of a secondary fire), but they're "customizable" due to an all new a build-a-bear- I mean gun mechanic. Considering you could have 3 (4?) in the previous titles and they all had secondaries, IIRC, it's a step down.
There are side quests you can do for extra "loot" (mostly materials used for gun-building), that usually end in you fighting waves of enemies that appear faster than even your strongest weapons can shoot. Game is, I believe, designed around co-op, hence the monsters en masse, as they're meant for two.
The story is bad. It's really really bad. And some insta-kill climbing sections that go on for too long. Oh, no manual saves, and the checkpoints suck. Still a decent game if you have a friend.
