But I'm completely bewildered by the FPS argument. Hasn't the only reason FPS not been feasible on handhelds because of inadequate controls? I think that's the entire point of the Vita's interface. I play shooters almost every day and I can't wait for the first serious CoD, Battlefield, or (gasp) Unreal Tournament that hits the Vita.
Theres many things that factor into purchasing an FPS for me...the biggest one is the online multiplayer competitive/cooperative with friends. If i can't play it in either one of those two, then its a much less likely chance for me to actually care about the game. Having those are huge bonuses to replayability, and for most of my games I like to keep and play them often. Single player can only do so much.

Another is control...I highly prefer a customizable Keyboard/Mouse over the Pad...although thats more of personalization, it just makes more sense to aim with a mouse. So yes its inadequate controls . The depth of field is pretty important too with the monitor imo, as well as the amount of players that would play a PC FPS compared to a Vita.

Thats just me though...I was always surprised at the fact that there are CoDs in handhelds. But hey if it appeals to some...i dont see why they shouldn't make one.