There was a long period of time where LibreOffice Writer had severe performance regressions due to a rework of graphics handling that removed most of the image caching. If you had a slower system or a high DPI / Retina display it could be agonizingly slow due to constantly rescaling images on the CPU. It started sometime in either 3.x or 4.x and didn't get resolved until mid ~7.x. I stayed on an old version for a long time.

Unlike Word at least you can still select all its options without having to run it maximized hogging all of the screen. I'll take that over over prettier and unusable.

I actually found it pleasantly similar to the older versions of MS Office, before we got the ribbons, also with customizable themes and actually a decent amount of layout options: https://imgur.com/a/libreoffice-ui-80hwOp0

What personally bothers me more is the performance, which can be pretty hit or miss.

Still, I hope the project remains going for the decades to come.

It's subjective. LibreOffice UI is why I stay away from MS Office. I can't find anything in MS Office anymore, I have to rely on their "search for command" feature (or whatever it's called) to be able to do anything. LibreOffice is mostly intuitive for me. On the other hand, my father does not like it and keeps nagging me to buy him the MS product (I can't justify the costs for his casual use though).

Which one? It has 7 different UI paradigms you can choose from.

Personally i like the "Single toolbar" UI, it only shows a menubar and a toolbar with the most common stuff, which i find a great balance between minimalism and discoverability.

Though i only use like 1% of LibreOffice's features - and really only use Writer (which i mainly use as a dumb rich text editor) and Calc (mainly for a few calculations one could most likely even do in VisiCalc :-P).