I ordered in October and took delivery December 24.
I don't know that I would say I have regrets, and I think knowing what I know now, I probably would have still ordered, with one huge caveat I'll come to later.
That being said, I don't feel nearly as warm and fuzzy about Tesla as I did back then. They have disappointed me in several ways. In addition to those mentioned (the length of time it took to get my seats, the range issue, the horsepower issue, the autopilot delay) I was really upset by the whole center console issue, as I now have a center console that doesn't match the rest of my car, with no idea if I'll ever be able to swap it for a console that does match. With respect to the previously mentioned issues, I felt strongly that Tesla should have been doing some things to attempt to alleviate some of the pain and inconvenience. For example, they could have done SOMETHING for those of us who had to wait five months to get our seats. I just have the sense that Tesla corporate feels they can do pretty much anything, and we as loyal supporters will remain loyal, and if they lose a few of us on the way, they're OK with that. That kind of cavalier attitude bothers me, particularly because of the way they have been acting, and what they have been doing. I feel like they have been taking advantage of the loyalty they have built up, instead of working to maintain it.
I have also had some wind noise issues with my car that have not been fully resolved, and I expect now won't ever be, since a tech rode with me, heard them, and said they were normal. The noise is better than it had been, but the cabin is not nearly as quiet as I expected it to be. So not so much a regret, but a disappointment.
The one issue that would absolutely cause me to regret having purchased the car if it is not resolved in my favor concerns ranger and valet service. I live in Ithaca, over 200 miles from any service center, with little likelihood of a service center being opened near me any time soon. I was very concerned about how I'd get service for the car, and asked lots off questions about this more than once before ordering. I was assured that at the worst, a ranger would come to me for $100, and if the problem couldn't be solved at my location, the car would be transported back to a service center, and then back to me, at no additional cost. I was told that the fee wouldn't apply if the issue was a warranty issue. Later, when I finally got to see a car in person, a sales manager at that location told me that because I lived particularly far from a service center, the $100 fee didn't even apply, and the ranger visits would all be free. In any case (meaning even if the second person was wrong), at the worst I was looking at $100 fee any time my car needed something, if it wasn't under warranty. But somehow, recently, officially this has changed. For now the official policy seems to be, "We don't care what you were told before you bought the car, or what policy was in effect then. We have changed it. Pay us $3.00 per mile one way if you want us to come to you and work on the car or pick it up and bring it back." For me that would come to $639 per incident, which is insane. My service manager agrees, and is working on my behalf to see what can be done, but if Tesla does not stand by the original agreement then yes, I will definitely regret having purchased my car. I will have no reasonable way to get service for my car, as adding $639 to any service visit, including those that are warranty service visits is an expense I am not willing to bear. But even worse than that, I will feel completely taken advantage of.
I'm giving Tesla the benefit of the doubt for now, and assuming they will resolve this as they should, in my favor, and agree to continue servicing my car under the original agreement. Assuming they do, then I don't regret my decision to purchase. I just have some disappointment, but of course am also very happy about many aspects of the car.