My experience:
I have been waiting before complaining about this. But I am really fed up. (Using iPhone 7 Plus. Only a few months old)
Let's start from the beginning of the iOS (public) life cycle until today with the official 11.0.2.
I used to beta test the Public betas since that program came out and most of the public betas were relatively stable. Not any iOS 11 beta. It was my fault for trying it on my primary device (although I never had such a major system failure on ANY other iOS Public pre-release before) but one of the later iOS 11 betas completely crashed and killed SpringBoard and probably other system processes to the point where the phone was a brick (no phone calls, messages, alarms) and I missed a flight (cost me about $70 US). Again, my fault and I downgraded back to iOS 10 when I was back from my trip.
Fast forward to iOS 11 GM. Installed. Immediately buggy, laggy, SpringBoard restarting itself, apps hanging and needing hard resets (at least 3 or more), battery draining to 10% in the time I would normally have about 40% left on iOS 10. Still very stupid graphical glitches you expect to see in the first one or two Public betas (such as spotlight search overlay blocking the homescreen, etc).
I decide to backup, put the iPhone into DFU mode, and entirely restore the iPhone firmware and software to a clean GM of iOS 11 downloaded via iTunes. No dice (just a waste of 2 hours).
iOS 11.0.1 is rushed out. I think it may help some issues. Battery seemed to improve but it may have simply been my usage. All other above glitches remained or worsened. Stability of apps degraded enormously. I am now hard resetting the device a minimum 3 times per day.
iOS 11.0.2. The battery issues are ridiculous now. I'm estimating a 30-40% higher drain than iOS 10 and a 50-60% high drain compared to the previous 11.0.1. Apps and Springboard crashing are now nearly every hour. Control center just hung and caused me to decide to post it. Bizarre erratic software behavior such as the control center hanging when I swiped it up and suddenly I look at the device and the clock app is opened for no apparent reason.
Social apps including KakaoTalk almost unusable. Black screen app crashes, force quitting frequently (and often needing to hard reset).
This is too much. I can't be even expected to THINK about spending $999 plus tax on an iPhone X (which is the phone I've been aware of and waiting for for over half a year -- all the rumors were pretty much spot on). But if iOS 11 is this buggy, I can't imagine the new scandal that will come out with that phone (AntennaGate, BendGate, whatever the new one will be... FaceGate anyone???) But that's another topic.
tldr; iOS 11 GM and 11.0.1 and 11.0.2 are still enormously buggy and nearly unusable on iPhone 7 Plus even will clean DFU mode install. FIX IT.
