XFCE isn’t as polished as KDE, and I do miss some features, like KDE’s excellent network applet that shows detailed statistics. But overall, the experience has been good, and I really appreciate how quickly I can unlock the screen after a pause.
I also enjoy the wide variety of themes. KDE has plenty of impressive dark themes, but very few light ones, and most of those fail to clearly differentiate the active window’s title bar from inactive ones. XFCE does much better here.
(Some people point out that XFCE doesn’t work with Wayland. That’s not an issue for me. My time with Wayland was highly frustrating, primarily due to the unreliability of keyboard layout customization. After months of struggling, I went back to Xorg and good old xmodmap.)