1) Any unlocking methods, except for a pin code, password or pattern, turn out to be very weak. Face ID eventually stops recognizing my face. And I doubt it changes so much in a week. The first few months after buying the phone, the function worked perfectly, but then recognition problems began. Now, using Face ID, the phone very rarely unlocks itself, or you have to wait quite a long time. Resetting Face ID does not help at all. The fingerprint is just terrible. Never used it all the time. As a result, you already score on all these functions and simply enter the password. This is faster, though more inconvenient. It's a pity, because I had high hopes for these features.
2) The back cover, although it shimmers beautifully with a gasoline stain, is made of plastic that is very unstable to scratches. I always carry my phone in a silicone bumper, but then I had to read the Troika card using NFC, and scratches from it immediately appeared on the back cover. It's scary to imagine what would have happened if I had worn the phone without a case.
3) Performance before upgrading to Android 10 leaves much to be desired. The phone was sometimes stupid with several open applications. Yes, even with the new android there are freezes with the opening of the keyboard, etc. 95 percent of the time the phone works very fast, but at some moments (fortunately - rare) there are disappointments. Apparently, 4 GB of RAM is still not enough. I can't say anything about the 6GB version. Given that now the difference in price is not great, it is better to take it. With no other apps open, the interface and current apps run very quickly and nicely.