On my gaming PC: I had a lot of random boots to black screen. (Vega 56 GPU)
USB ports did not function at all with USB drives.
TF2 had terrible performance compared to windows.
There was no way to configure my sound card settings.
I still run Ubuntu + kodi on my HTPC, have done for about 10 years. Updating versions of either can often lead to time spent in the terminal. Usually nvidia gpu related. So far the issues have been overcome.