I've enjoyed N since it was a beta update, for sure by the 3rd or 4th beta build. I've never had a real problem with it, and I'm a big fan of N notifications. I'm currently running 7.1.1 on my 2 Nexus 6s--stock on one, a custom rom on the other. Both are fine, and if I ever get a downgrade notification to 7.0, I won't accept it. (But that's specifically a Nexus 6 update issue.)
Bear in mind that it's tough to get a clear idea of why any OS works for some and not for others because we're never getting the full story about any phone or any phone user. People rarely admit that they have nearly zero room left for storage or that their app drawer is full of crap from iffy 3rd party sites or that they've drained their batteries every other week for the past year and a half or that they wouldn't know how to clear any cache if you threatened to force feed 'em chocolate-covered brussel sprouts and on and on and on.