1) It's fast (very fast).
2) It looks great.
3) The in vehicle display looks fantastic, and is extremely responsive. It feels like the difference between using an iPad or using a cheap ($50) android tablet from aliexpress.
4) The in vehicle speech commands are excellent.
5) The autopilot is excellent.
6) The mobile app is excellent.
If you are seriously confused as to why Tesla owners are so fanatical about their cars: go drive one.
It shouldn't surprise people that these vehicles are sold out for the near future. They're actually just that good.