Crispy Gamer is serving up an interview with Gears of War 2 lead designer Cliff Bleszinski:
Crispy Gamer: Have you made any fundamental changes to gameplay, like to the cover system?
Bleszinski: I'm not a fan of how developers tend to hate on their own games. "Our first game, even though it sold a ton of copies, was crappy." What's wrong with you? But I have to say, after playing Gears 2 for so long, the cover improvements alone are just amazing. Whatever you want the A button to do, it just does. It was amazing in the first game, but there were a couple problems with players unintentionally getting into cover when they didn't want to. So we're polishing it until it shines. We made something like 500 code tweaks to the system, so now there are never any instances of someone going into cover when they don't want to.
We've also added Stopping Power so players will physically slow down when they're shot with bullet-based weapons. This fundamentally changes how multiplayer is played since it prevents people from doing that cheesy shotgun roll thing they've adopted. Oh, that drives me crazy.