While I've had a pretty negative experience overall (very poor initial build, later VIN mixups, early April VIN is stuck in Fremont for no clear reason), virtually everyone I speak to at my local Service Center and Tesla in general are patient, kind, and intelligent. If I was to complain about anything, it's that Tesla corporate seems to do a poor job informing them and overworks them in general.
This all of course rolls downhill to the customers, but I think it's important to remember that the SAs are just doing their job. I'm convinced that 99% of our frustrations are born out of corporate's policies and overall structure.