You can completely play an FPS on a console with a gamepad. It's really not hard and it's been proven to be successful. It's just when you're used to playing a skill-based FPS game (particularly a multiplayer one) on the PC, you're going to be like... WTF? The experience is just totally weak in comparison. On its own, it's fine, and with SP games or games that don't require the same level of accuracy or have the same level of intensity, it's cool. Just seems a bit odd in comparison, really, because the fact is that a KB/mouse setup is always going to be better no matter what you do.