A little off-topic, but how do you people stand using the keyboard? Or do you hook a PS3/Xbox controller to the PS3?
It's far easier to aim with a mouse, IMO. It allows considerably more freedom of movement and you don't need to push anything unless you want to shoot or zoom.
On keyboard, using it is little different from console controller. The buttons you are using are still all under your left hand so once you learn their places, the keyboard isn't an issue.
On the original question, I recommend getting the GOTY for PC version. That way you have so much extra content from mods and DLC that you will feel you're playing a whole new game.