I haven't come across many bugs at all in the game after three single player seasons and an online co-op championship. What i've come to dislike are less bugs, but things that are just poorly designed like the way the AI moves unpredictably to spoil qualifying laps and how you can't just skip practice. At first it was refreshing in 2010 but hundreds of races later it just seems like a pointless withdrawal from the action. And of course David Croft, for anyone who's completed at least two races..
In short the career mode is crap. The online co-op mode is wonderful if you have a similarly skilled 'team-mate' and the racing feel is as good as ever.
I'll be polishing off the four remaining achievements over the next couple of days but after that i'll be moving on.