I wanted to use KDE 4 when it released, but it kept crashing on my machine. I would update it every once in a while and try again but issue would always pop up. By the time "plasma 4.4 is stable" was declared, I had lost interest and started using tiling window managers .
That said KDE 6 is pretty solid. I rarely have issues with it.
That said KDE 6 is pretty solid. I rarely have issues with it.