I'm on 7.10 and have come all the way upgrading from 5.4 without major
issues except for one of the first upgrades when my keyboard stopped
working in X - the meaning of the "LA" keyboard configuration was
changed from LatinAmerica to Laos - it took me a while to solve that ...
Other than that I'm very satisfied with Ubuntu and have been using for
more than 3 years as my main Desktop at home.
I'm updating my box using Update Manager on a weekly basis - knowing
that some upgrades have bad side-effects or put the upgraded software
out of service until a new version appeares (usually within two weeks)
I suppose this is the case for Skype - recently upgraded from 1.4 to 2.
It used to work perfectly and now only the licence acceptance window
appears (empty) and closes after one or two seconds - there is no way
to start Skype.
I have not found anything similar so far using Google - maybe someone
from this group can help.