Since I only just received my M3P in late September I didn't really have an attachment to the old UI.
Although I don't understand some of the changes, I don't dislike the update. For me it's not better or worse, just different.
Well, I have had my car for almost three years now and have witnessed lots of changes to the UI. Some I liked, some I disliked, but the overall direction I never disliked - until this time.
Up to V10.x the lower icon bar in the home screen had all the vital buttons in it all the time. Windscreen defogger, defroster, seat heater, wiper controls, music, camera, climate temperature, everything.
Plus on the lower left of the screen you had your tab for your trip info. Unfortunately I had to activate it again everytime I started the car, which was a nuisance, but at least the info was available permanently and unobtrusively without taking away anything relevant from the rest of the screen.
Now, the trip info is gone and the part of the screen where it used to be is totally dead real estate, unless I signal and see the camera image. Most of the time it is totally blank. If I want my trip info, I have to go to the vehicle settings menu, and then the trip info fills the entire main part of the screen, where the nav screen should be. No use while driving therefore.
Now, when I need the windscreen defroster, defogger or the heated seats, I have to first bring up the climate control menu, then look for the appropriate button, all while taking my eyes away from the road. What's that supposed to be? Where's the improvement in making things more complicated and hence dangerous?
I find it highly disturbing that Tesla now appears to favor multimedia functions over safety related functions. Seriously, how often do I need to rearrange the multimedia and entertainment buttons along the bottom of the screen? Can't this be something that is done via the vehicle settings page, while the important safety related stuff stays where it is instead if being hidden away in some submenu?
Honestly, I have loved driving my car since day one. Ever since I got the V11 update I absolutely hate every time I have to drive it.
If this is the way Tesla is going to move forward with their UI, this will not be my car for much longer, and the next one won't be a Tesla anymore either. After all, by now there is enough very attractive competition around, something that just wasn't the case when I bought my Model 3.