> still internally consistent

The most internally consistent design was that of NT 3.1 - it was a true classic in many respects. As far as general usefulness, performance, and versatility nothing can compare with Windows 10 (except Linux, of course).

I am not arguing about NT 3.1, but what inconsistencies were there in Win7 UI?

Starting with Win8 you have basically a random choice if some setting is set in "classic style" or new fancy "settings" dialogs. You can have all the performance in the world if your users spend most of the time just looking for the right place to do something.

Windows 7 has basically the same problem with settings. You have the dumbed-down, XP-style control panel that doesn't expose all the settings, and the hidden classic versions of the settings.

For example, the useless user settings in the control panel and the more useful old version in "control userpasswords2".

oh, OK - I entirely forgot about this :). But it's still just an easily modifiable default for beginners that power user doesn't have to use (or indeed remember in my case :)).

In Windows 10 you have two different kinds of UI and settings that can be changed in one but can't be changed in the other and vice versa.

Win7 is nice too, but I admit I didn't use it much (as I was a Linux user almost exclusively when 7 was released). I got Windows 10 on a new laptop and gave it an honest try (along with the new Linux subsystem), but the little annoyances and inconsistencies piled up, and back to Linux I went.

I spent a lot of time with Windows 2000 back in the day. Windows 2000 was the first OS I bought retail -- my new PC came with Windows ME and it was so terrible I ran out and actually paid for an OS ;)

Windows 7 adds some nice things like search and the explorer shift+Rclick menu, but it also hides some settings panels that haven't changed since 2k behind more clicks.