In brief, the answer to your question is no, as far as I can tell.
Differences are in the mint update app (which you may or may not have) as well as some other more subtle differences which are in the code of the whole operating system (since it is based on updated ubuntu, which has changed bits of it in the last few months) throughout (someone correct me if I'm wrong here please!).
Differences are herehttp://www.linuxmint.com/rel_daryna.php
but there will be changes in the codebase that aren't written about in the release notes (that I can see, anyway)
Hope this helps. I am unable to go into the details of what has actually changed under the hood, as it were, since I'm no programmer, but there are updates and changes in the software repos as well, basically a start of some differentiation between mint and ubuntu
, but, if you have working 3.0, why change (well, you may as well keep it until it's support runs out