The Mail, Calendar and OneNote apps kept me hooked. But the lack of a decent terminal was killing me. Also, Skype didn't work properly half the time and the new "Video" and "Messaging" apps built on top of Skype were crashing 90% of the time.
Then your installation is clearly broken. No, it's not good, but let's not pretend these issues didn't exist in the "good old days".
OSX, iOS, Android, Linux, and Windows all have pretty big issues when doing upgrades.
There's the occasional odd package under Linux which remains installed and you need to manually remove it, but nothing unfixable. But I guess that depends more on the underlying OS structure. I'm looking forward to see more widespread usage of Snappy Ubuntu.
Since that is the main way people migrate to Windows 10, I would've expected them to be more careful with it.
RHEL only started supporting it for the transition between 6 and 7 on a like 3 architectures on one edition.
And OSX has it's share of issues. For me personally, updating to El Capitan was the worst upgrade processes i've done in recent memory. From not running the installer but giving no issues, to not finding the harddrive during the install process, to corrupting the current install of yosemite, to bluetooth being broken after the upgrade, and i can't get wifi speeds over 1mbps.
A clean install solved all of that, but that's pretty normal with every single OS i've ever encountered.
It's not a question of being "more careful", it's that writing software in a way that it can be in-place upgraded to something you don't know will exist at the time is EXTREMELY HARD! I really feel it's one of the big "unsolved problems" in computer science and i don't see it being solved any time soon.