I've never had a problem with the Ubuntu upgrade procedure, and have upgraded several times now.
With different versions of Ubuntu, I have had problems with graphics tablets breaking, suspend to disk suspending to RAM instead, and virtual screen resolutions being bigger than the graphics chipset can support, but as far as I know these are all OS problems and not anything to do with the upgrade procedure.
The official recommended procedure to upgrade Ubuntu from the command-line is as follows. I believe you have to run this once for each version; you can't skip versions when upgrading Ubuntu (except to upgrade from one LTS release to another).
sudo apt-get install update-manager-core
jdkaye's advice should also work, but do-release-upgrade has a better chance of migrating configuration files safely.