John Gruber has had a tight relation with Apple for about fifteen years now. One of the better watchers, he calls out problems as well as noting the good. Here's his first iPhone Xs commentary. (I wouldn't call it a full review) as you might expect it is mostly about the camera.
Tomorrow my iPhone 6 turns four. It has a few issues, so it may finally get replaced. On the other hand I put iOS 12 on it yesterday and am seeing snappier performance and some other general improvements.