Another European here (Belgian). Love the car, love the handling, love the acceleration, even love the paint ;-)
The only thing that's been disappointing so far, is TACC and autopilot. Had a few phantom braking events (scary with a car behind me), but even in its normal operation I don't like the way it drives. It's constantly cycling between acceleration and regen, often even lighting the brake lights. Since I hate driving behind someone who taps his brakes every 10 seconds (you never know when it's real braking or just another meaningless tap), I really don't want to be that kind of guy myself. Also, it's very inefficient. Cruise control is normally supposed to save energy, but I'm sure I use less energy with TACC off. Also, the transitions are not smooth. One moment you're accelerating, and then in a tenth of a second it switches to regen, and half a second later we're accelerating again. No anticipation, no smoothing, just binary reactions. I always try to smooth out the speed changes of the car ahead of me, but the Model 3 actually amplifies them. And if someone cuts in ahead of you, the car immediately brakes, creating dangerous situations and traffic jams behind you. Absolutely awful.
Lane change is also pretty bad, it's basically unusable. It often refuses to change even though there's plenty of space (but you're blinking so cars behind you start to accelerate in anticipation and then have to brake as you're not leaving the lane), and if you don't hold the blinker it sometimes actually jerks back mid-maneuver (for what possible reason would that EVER be considered safer than continuing the slow lane change?!). Also, the car sometimes brakes even though you're changing into an empty lane. Europeans normally change lanes a lot because we have to drive on the right whenever that lane is free. Middle and left lanes are only for overtaking. But with Model 3, you need a mile of free space to change to the right lane or it will refuse, brake, or both.
So basically, I just have AP as a gimmick to try once in a while, hoping it will get better, but not really using it as intended. I keep trying it, since I'm a bit of a geek and love technology, but I keep getting disappointed and turning it back off. I don't want people to think I drive this badly.
I just got 2019.8.3, haven't tried AP on that version yet.
Anyway, the rest of the car is absolutely great. Never regretted buying it, and I'm hardly driving our Merc anymore. Even though I have to drive more slowly (still above the speed limit, but not as much) to make it without recharging. It's worth the extra 10 minutes of travel time. (edit: My commute is 314 km, my Merc does the round trip at 160 km/h, the Model 3 makes it one way at around 140 km/h)