I bought one of these from China, using it right now (in the US). It definitely has some quirks, but does what I bought it for (gaming) very well indeed.
After setting up Nova Launcher, using button navigation, the home button would only go home from certain places (such as the app switcher). Also the nav buttons were not centered - instead there was a Taskbar with some of the system apps, and I couldn't change which apps were on it at all (besides disabling the apps themselves).
So I had to finally learn gesture navigation. It's not as annoying as I expected it to be. I actually like it for the most part.
I had to change the font to the AOSP one instead of Lenovo's one because in some places it added extra spaces to apostrophes, but conversely I had to switch the system spell check from AOSP to Gboard because it was marking as misspelled any word that was followed by a period. (Like that one, or this one.)
It doesn't support work profile and therefore apps like Island or Shelter - but does have a built-in app copying system. It's not as good though, I copied Chrome and couldn't find a way to log it into my 'alternative' Google account (or even my regular one) because it says I have no Google account, then it opens Settings in my normal profile - with the account(s) - instead of the empty copy profile so I could add one the copied Chrome could see. (Can't copy Settings or other system apps either)
Still no GPS, which is not as much of a problem for me as it used to be when I played Pokemon Go all the time
Stuff like that, nothing I'm considering a serious problem.