Not for me. I switched to Kubuntu in 18.04 LTS (after many years of OpenSUSE, so I've got a pretty good idea of how a polished KDE distro looks.) No complaints at all. Kubuntu use to be a poor rendition of KDE but it's working great now.
I'm pretty happy with Ubuntu generally; kernel-hwe is outstanding. With 18.04 LTS you still get updated kernels; it was released with 4.15 but with "hardware enablement" updates it's up to 5.3 now.
I tried Kubuntu this week, and it’s the first time I’ve seen a desktop linux distro where everything works, and the experience is not made miserable somehow by poor font rendering or lack of suspend/resume or external display capability. I put lots of this down to Ubuntu but also a lot of it to KDE, so I’d be interested in knowing why Fedora is supposedly an improvement?
Not for me. I switched to Kubuntu in 18.04 LTS (after many years of OpenSUSE, so I've got a pretty good idea of how a polished KDE distro looks.) No complaints at all. Kubuntu use to be a poor rendition of KDE but it's working great now.
I'm pretty happy with Ubuntu generally; kernel-hwe is outstanding. With 18.04 LTS you still get updated kernels; it was released with 4.15 but with "hardware enablement" updates it's up to 5.3 now.