Well, this was covered elsewhere, they don't even like putting info out that they are obligated to release to continue having software that they use (GPL GNU public license - look it up, they are violating it on a number of components). They don't mind to lie to you to stall for time and never resolve any of these things when confronted which really puts me off, btw.
They blacklist cars of researchers that gain their entry into the car systems, the blacklisting deprives such cars of (most of) updates, the blacklisting restricts ability of service centers to perform work on such cars (need engineering approval to perform a lot of operations => prolonged repair times as the result). For example the two last updates my car officially got were 17.50.2 yesterday and 17.24.x in August.
I was most disappointed by how outdated (and slow) interior hardware components were, and software too (somewhat improved now, but very slightly)! The architecture was a product of a true startup-like mindset - cobble something together that kind of barely works for the most part and ship it, then barely patch it up as issues crop up to just keep it (mostly) afloat. The take 2 on the model 3 and ape front is more organized and lately they even started to put good effort into the security side of things, but current S/X systems appear to be a writedown at this point on the Tesla side which should be a concern (esp for new owners) given that they still sell these systems.
Quality control on the software side is such that the manufacturing QA seems to be a shining example of perfectionism in comparison (another throwback of startup mentality?), when you look inside, things are crashing left and right (not always in user-visible manner, but every time you enter the car and the full player got minimized - that's a sign that underlying media player has crashed). Spotify server is particularly crashy (did you know spotify-server is running on your car even in North America when the functionality in just the UI is disabled?)
What I was pleased with? Well I was pretty pleased with how easily the entry could be gained, I guess.
Also they run Linux (well, I already knew that by the time I bought, but I still like it). Inside there's a whole network of different compute nodes, not just one cramped node that's common with other manufacturers (for cost reasons mostly - why have 2-3 computes when you can have just one driving multiple displays and other business logic). Hm... slim list on the positive side I guess.... Ah! It was fun to play with too