It's just tradition. Traditionally people hate/like every other release of Windows. They hated Vista, liked 7, hated 8, like 10. They will hate the next release whether there is anything wrong with it or not, and they will like the one after that whether it has problems or not. Every Windows has had some problems and some good parts to it.
Vista sucked. Windows 8 sucked. The hate was largely MS's fault. Now some of that hatred was over the top, but still, I'd say most of the hatred was deserved.
Windows 7 was a huge improvement over Vista. Similarly Windows 10 is a huge improvement over 8.0.
There seems to be a lot of bandwagoning of praise for Windows 10. I doubt these people are truly being objective, or even care to be. I find there to be a lot of uncomfortable faults with Windows 10. It's hard to believe that real enthusiasts agree with the forced update, protection, and nanny rules with this OS. Perhaps turning off the brain and forgetting about what goes on behind the scenes fills that appeasement. The superficial gleam doesn't work for me.
Overall, I quite like Win 10.
The thing I hate most about Windows 10 (besides the niggling bugs in this early release version) is the fact that the invasive privacy features are on by default. They should be off by default.
As for the updates, I am sort of used to it since on Windows I usually update everything anyway, and on OS X, the updates get packaged together as point releases so something like 10.7 would have 5 "service packs" over the year, not thousands of individual updates like on Windows.
So, weighing the plusses and minuses, I'd say for Win 10 the plusses outweigh the minuses for me for home (not enterprise) use, whereas for something like Windows Vista, the minuses far outweighed the plusses.