Playing with keyboard is fine, and an accomplishment to brag about to boot, just saying that the people complaining about it always have the option of plugging in a controller. Kinda negates their complaints.
I might try it, at some point, though normally I only play the more realistic ones. Gran Turismo is a favorite, I hear good things about Forza but I won't touch another Xbox in this lifetime, TOCA Touring Cars was nice and DTM Racedriver was pretty awesome too. I'm not sure SHIFT is on the same level.