The only time before this I've felt like Apple took a huge UX or appearance dive on an OS upgrade was iOS6 -> iOS7. People complain about almost every macOS upgrade, but the closest they've come to bothering me is that I hated the new tab styles in desktop Safari they introduced a while ago, but that was configurable so I just set it back to normal and that was that. I've disliked other things (the Touch Bar was never anything but a way for me to accidentally open Music—I basically had to disable it to make any of those MacBooks usable) but never really been bothered by an OSX/macOS update's appearance.

So, I didn't expect to mind this at all, despite lots of people apparently hating it.

Then I upgraded. And yeah, it's remarkably shitty looking, first time I've agreed with the "haters" for a macOS release. It looks like an above-average GTK theme, which is to say, awful. Plus they found a new and different way to make Safari's tabs look like crap (and I'd swear tab manipulation is super laggy now, where it wasn't before) and this time I can't fix it with a settings toggle. Like, that element specifically looks and feels like it's from a below average GTK theme.