Well, finally decided (just having a boring lecture right now).
Anyway, if you have a fresh install of Lucid and trying to upgrade to Maverick, you can wait forever for Update Manager to propose a new distribution for you. The problem is in Software Sources settings, where new distribution notifications are set to 'LTS Only' (Lucid is LTS release).
To fix that and switch to regular update cycle, go to
System / Administration / Update Manager / Settings...
and set 'Release Upgrade' to 'Normal Releases'.
Update and enjoy. I hope to write a note on what is broken with the new release.