A few weak FPS games from this gen I can remember.
-Clive Barker's Jericho
-Section 8
-Timeshift
-Call Of Juarez: The Cartel
Recently: 007 Legends and Medal Of Honor: War-fighter were meant to be pretty awful.
Honestly, those of you mentioning Halo or Killzone must not have played more than a handful of FPS games. Those games have good visuals, high production values and some solid gameplay. To compare them with some other FPS games this gen would be night and day really. Some truly awful FPS games have been made.