First of all - name. Utopic Unicorn? Come on! That animal even don't exist. Was Canonical try to tell us something through the name? Maybe. Think about that...
Second - good thing about Unicorn was that developers warned us to not expect much from new version of Ubuntu. It's interim version, as all .10 versions are. But then, some official Ubuntu blogs wrote about how to upgrade Trusty Tahr to Utopic Unicorn. To be worse, they claimed how it is safe to do upgrade through System Updater, from running system. Of course, many users did this and now they asking how to downgrade their systems.
Please, do not upgrade to Utopic Unicorn now.
If You are using Your machine for work, stick to the LTS versions. But, if You want to upgrade anyway, do it in another way.
- Download Utopic ISO
- burn it to DVD or put it on USB
- create backup of Your Home directory (You must not do that if You have Your Home directory separated from root)
- Do clean install
- restore backup of Your Home directory
Great things about new Ubuntu release are the new versions of some programs, new kernel... But, my advice to You is wait a bit before You do upgrade to 14.10. Let some things come to their place, and if You must, only if You must, do upgrade.
I didn't try Xubuntu, but I saw screenshots. If that purple colour is now the default colour for highlighted background - it is disaster. If not - take my apology.
And here we come to one of bright points in "Utopic" family - Ubuntu MATE. It's first Ubuntu version with MATE DE, unofficial version. There are rumors that MATE will become official Ubuntu DE in near future. Great look, good old Gnome2. Yeah, we'll see...