I've played and enjoyed many PC shooters over the years, but I actually like the mouse least, since it seems too accurate and fast... seems very artificial, like you're not really controlling a character on screen.
The gamepad can be done well: Halo2 controls great: also it's nice to be 'lazy' while playing games sometimes which a gamepad is perfect for. Although it can also be incredibly frustrating (thinks to trying to pull off hard shots in RE4: which should be much improved on Wii).
COD3 for the Wii I enjoyed WAY more than I thought I would, almost completely oweing to the controls. The game was downright tireing to play, since you had to stay constantly on edge, but it was incredibly engageing. After initially being totally confused by the controls, they soon became more natural than any other system could ever be ... OTOH Red Steel controls were a mess: I didn't get past the first level before giving up.
