Well, i like both methods. Its impossible to be competitive using a gamepad when playing online, its not impossible by any means, but you sacrifice accuracy.
What you do benefit from is 'the couch'.
you can sprall out and play as you would a console fps. It makes the game a little bit more challenging, imagine playing with a mouse but you have no crosshair, its the same feeling.
Im currently playing FEAR, no use of slowdown and on hard difficulty and its good fun.
COD2: good fun, doesnt have the slight auto aim of the x360, can be difficult with the sniper rifle.
Half Life 2: exactly the same as HL2xbox, but no autoaim (its not a big deal). i find the weapon select a bit tougher, due to having to 'scroll' with whatever you mapped the mousewheel, but you can hotkey the G-gun for instant grenade grabs.
Battlefield 2:
controlling vehicles is much easier i think, especially flying. Just dont pick a sniper class, pinpoint aiming is difficult.
GT Legends:
great control and if you adjust the throttle and the break sensitivity, you can have near perfect trigger control on both.
Toca 3:
same as above.
added:
SWAT4:
you can map all the commands beautifully and it works quite well.
Except for the sniper team. you wont have enough buttons.
Which is a pain.
FEAR:
tremendous.
Lock On:
for 'pure' dogfighting, it works well. you will need the keyboard to land and takeoff
Operation flashpoint:
Fantastic with vehicles, iron sight aiming takes some control,
