Pretty painless - I've just ran this on two servers (not in production):

    sudo do-release-upgrade

or if you're on a server

    sudo do-release-upgrade -d

although they don't recommend doing that on a production server because the .1 release usually has a lot of bugfixes.

It took about half an hour followed by a reboot. Occasionally had to intervene to tell it to overwrite config files I hadn't touched or to let me do a merge if I had.

Obviously make sure you have backups first.