I bought my first model S back in 2016, first registered 2015. My only gripe then was that I had to put a non refundable deposit of £1000 before they would bring the car from Heathrow (I think) to Birmingham for me to view and make a decision.
Having said that, the car was in immaculate condition and I have had nothing but excellent service from the Birmingham SC then and since. I purchased a new model S in June 2019 and once again the experience was very good. I did, however sell 'privately' to R Symons as their offer was 25% better than the Tesla offer.
The Tesla experience is certainly a mixed bag with many people having need to vent their feelings about poor quality/service. But there again people that are satisfied are far less likely to feel it necessary to advertise that fact.
Just my 2p worth