Windows 10 UI is objectively bad on a lot of points like consistency, search from the Start menu, etc. At least up until Win8 you could switch to the classic theme to get something looking like 98’s UI. Now you have no choice but to suffer the big button dialogs made for tablet on any laptop / desktop without touchscreen.
It also inherited a ton of bad habit from Windows 8, such as shiny fancy-looking but overly simplistic configuration screens, except the original configuration dialogs are still there underneath. This is indicative of a bad development methodology: devs/teams work on useless small projects (jazz up these dialogs so that grandma can use them) which can easily be executed and completed within a year or so (you know, a review cycle). While leaving all the old mess little changed underneath (because of course the new shit is horribly incomplete and doesn't actually fully replace the old controls). They have a corporate/dev culture which actively discourages long term incremental improvements of core components and focuses instead of trivial window dressing that can be packaged up in a SMART-goals format so that people can tick off their commitments and get their bonuses, raises, and promotions.