I have been at the service center in Van Nuys, Torrance, Costa Mesa and Buena Park. They are all very professional and helpful and do great work. Never had a bad experience once and I have had a total of 12 (or so) visits.
While that is great, the issues that some of the cars have are still there and frankly all the service centers can do is 'patch it'. For example the rattling noises from my headliner and dash board. Various attempts to fix these never had any success. In one case they even made it worse. The lose fit of my driver's seat is 'to specs' according to Tesla. My drive unit had to be swapped out 7 times (in once instance they had to swap out two DU in one service visit). Not at all the fault of the service center. They are getting the parts from Tesla and do the swap.
So yes the service centers are pretty awesome. Never had such a great experience with any other car I owned. Some of the quality issues are just not easily fixable.