Gears of War is pretty bland, especially Gears of War 2. I mean, the backstory and everything is kind of interesting, but the actual story shown in-game is ridiculously cut-and-dry. "Oh, look, enemies. Let's go kill them. Oh, look, bigger enemies. Let's kill them. Oh, look, a gigantic enemy. Let's kill it. Oh, it's the end of the game. Really? Alright then."
Really, though, all the stories with space marines versus aliens are pretty much the same, and they all look pitiful when you compare them to the Warhammer 40K universe.