It's very fast and reliable.
3 issues though:
1. fingerprint sensor went crazy and hardly recognizing myself. I have slightly sweaty hands, but still, it is worse than when I bought it. The percentage of succeeded readings is pretty small. At some point I deleted the fingerprints and registered them again(hoping will be better). Maybe than it got even worse.
2. Wi-Fi speed is pretty slow. I compared it to my old z3C and most of the times, z3 won... And even worse, the ratings were not so good overall. Somehow, I can "feel" that.
But it's not as bad as it sounds.
3. Phone idle consumes more than twice the battery consumed by "screen on". Sad, but I still get over 4h of SOD. Maybe Android Pie will be better here.
All of the issues are "fine" to live with. And there still is no better option for a compact device.