Today I tried Plasma 5.10.4 on my Arch and loved it. I am coming from Mac OS X, then used GNOME 3 and then Plasma. Never used KDE before, but plasma catched my eyes.
What I liked : 1. Customizations and ready to go. I never needed to boot Mac OS X for my daily tasks. 2. Flat UI 3. I can find what I am looking for within 5 secs.
What lagged me : 1. Wayland is unusable on Plasma (Let's work on it), random crashes
2. Aliasing issue with SFNS fonts (Apple fonts)
3. I didn't like the minimize, maximize and close bottom style of breeze. Make it flatter a bit more.. like Windows 10 ish, but not exactly (not matching those " ^ " things with other icons)
4. Focus more on notification and dashboard window overview. Let's bring Wow factor here.
5. An integrated dash dock would be better (not by default)
6. Sometimes upper left hot corner doesn't bring windows overview, and sometime it does. (Its shame and we should focus here)
- Myself, GTK+ programmer, a CS student from India, GNOME Nautilus hacker.