I use the eagle eye with a logitech mouse and nostromo game pad and after spending a few days tweaking the settings I got it to work well enough to make playing FPS games on the PS3 fun after being a life long keyboard and mouse player on the pc and never doing well with the game controller.
I would estimate it has about 70-80% the 'feel' of pc gaming but it is not nearly as precise. The other problem is the logarithmic input of the thumb controllers being converted from a mouse input. This makes spinning around to do a 180 or 360 near impossible. If you can live without that acceleration mode, this may be a good solution for you. I play BF3 with it and I like it far more than using the ps3 controller.
55" LG OLED | Networked Yamaha RX-V573 7.1 AV | BIC DV-32CLR Center | JBL 2600 Mains | Fluance AVBP2 Bi-Pole Surrounds on Soundcast SCS-100 wireless surround | 15" Polk Audio Sub | Networked Sony BDP-S590