I've been using iOS 11 on my test iPhone 7 for every developer beta release. I have restored my iPhone 7 to factory via iTunes 5 times. Apple has given my phone a clean bill of health twice. From the first beta up to and including 11.0.2, I have consistently and continually experienced freezing, random phone restarts, and slow performance (10+ seconds to register a key press or click)
I don't disagree that this could be a phone issue. It's early and I expect the problem, whatever it is, will be resolved. Until then, Apple telling me my phone is fine and the OS is fine leaves me up in the air with an unreliable device. If this were my primary device (still running 10.3.3) I would be more upset.