I didn't have too too big a problem with the original, bug-wise.... Until the car pack which brought about numerous crashes. The road surface was shite, too, which completely ruined it.
Judging by the Gumpert screen, the road is smoother than it was in the first installment, but it's tough to tell. If the roads are smoother and the crashes have been fixed, I'll most likely buy it for something different to play. Time will tell..