It's not so much the actual gameplay, more the setting. I mean for god's sake, every year seems to bring with it five hundred more 'army of today'/'army of tomorrow' style games. Rainbow Six, Call of Duty, Halo, Gears of War, Resistance, Killzone, Ghost Recon, hell there's even a new Doom game in the works, you know HL2E3 will be out this year and right in the middle of this market saturation the Duke will most likely awake from his millennia-long coma.
The annoying thing is, these games are all good. They're all playable. But they're all... samey. They seem to blend into one. It's about time someone actually tried innovating rather than 'slightly tweaked engine' or 'new weapon or two'.
On that topic, note the one recent fps that I DIDN'T list at the top- Bioshock. THAT's an fps that really turned the genre on its head, in my humble opinion. And yes, Portal too- games that require some brains to complete rather than pandering to dribbling teenagers who just want to shoot everything.
I know what to expect- 'if you don't like them, you don't have to buy them'. No shit, Sherlock. Precisely why I don't. But I can't help but feel that while there are studios churning out shooter after shooter, they could be producing something like Portal, or something new entirely.
Rant over. Congratulations if you made it all the way to the end.