I upgraded directly from Ubuntu10.04-4LTS to Xubuntu12.04LTS. I'm also using a
separate /home/my_user_name partition and VirtualBox and I had to reinstall most
of my favourite applications, which should normally not have been a problem as
data and preferences were stored in my /home directory. The upgrade ran fast and
smoothly.
However and BEWARE, I typed too quickly on the keyboard when I entered my
user_name and I mispelled it. Result : my old /home/my_user_name directory was
not anymore recognized.
A small mistake and many hours to recover from its consequences, I had to
rename, delete directories and edit the path in the preferences of each
application in my /home directory.

Anyway I like Xubuntu12.04LTS and feel it was necessary to upgrade as some of my
favourite applications, like fldigi are not anymore updated in 10.04.