I just finished installed Red Hat 8.0 on my main development machine.
The installation has managed to completely destroy the desktop configuration I've spent 5 years refining to my tastes. It took the liberty of switching my window manager, and is not giving me a clear means of switching it back. There are Windows-like "Home" and "Trash" icons in the upper-left corner that I cannot (easily) get rid of. The asclock application, my timepiece of choice, is not available. None of my TTF fonts, which Xfs is configured to find, are available.
I attempted to set up programs to be run at session start. xmodmap, which I use to re-map some keys. ssh-add, since I run my session under ssh-agent. gkrellm. When I re-did all of this (and why is it that this oh-so-spiffy desktop couldn't import that?), it hung the start-up sequence, forcing me to kill it from a different virtual terminal.
In short, Red Hat has succeeded in bringing the Linux desktop up to speed with Microsoft. I have had almost all choice taken away. I have never before today been so glad I no longer work for these people. DO NOT UPGRADE, unless you want your environment spoon-fed to you by people professing to know what's best for you.