I sold my 06 330i with the knowledge that the M coupe I was about to purchase was very far removed from the 330i in both comfort and performance. The car is a rocket, but you feel every bump on the road. Also, the "premium" sound system in the M is sub-standard at best. Again, know what you are getting into before you buy. If you are willing to sacrafice comfort for performance, then this is the car for you. It was for me.
330 hp and sweet exterior design.
Bigger wheels with fatter tires, better cupholders, and a better sound system.