Looks cool but how would you move forward and backwards and jump or crouch? Much less do anything else that required the keyboard.
It's very cool don't get me wrong, but it lacks a lot of the needed functions to play a normal FPS. Have good movement in a FPS is just as important as having good aim IMO.
I'd love one if they have a way to deal with the other needed aspects in regards to using your keyboard.
edit...
ok I just noticed this was for the PS2 not a PC. I thought it was for a PC when they called it a wireless mouse.