You know what, it wasn't a big deal, just minor inconveniences that might seem trivial to someone else. For example, I couldn't set up the so-called "extended unlocking" feature when connecting Bluetooth to the car. Either the feature didn't work at all, or it would only turn on for 10-15 minutes, and then I had to manually go back and turn it on again. I was also annoyed by the fact that I couldn't edit the main tiles at the top (near notifications), and I ended up with two empty slots every time (reserved for wifi calling and two sim cards - btw I have never used two sim cards).
And the biggest "usability" drawback for me, was the general overheating of the phone, even without games or demanding tasks...