I have a 650s with 14,000 miles (15 months) and have had no significant problems. That said, the "Navigation " is too complicated to use, and the rear camera software is so slow as to be ineffective.
Whether driving hard (almost always drive in "Track" modes) or just put-puting around, the "feel " of the 650s is like nothing I have experienced before. I completely forgive the car any foibles or irregularities it has-how would I replace it?
I like it so much next week I am paying $2,000,000 cash for a P-1 with 127 miles on it.