I installed ML when it came out first, but having a Lion partition on the same drive as ML caused some problems between iTunes and syncing the iPad and iPhone. i.e. I became frustrated when I had set icons on the above devices just as I wanted them using Lion, only to find them moving all over the place when I ran iTunes on ML.
While having problems with MyFiles, a new Cloud app, I had to dodge back and forth between the two OS versions, which gave me the necessary urge to sort things out. This has taken a couple of days, and no doubt there will be other apps which need to be updated, paired, or sorted out in some way or other.
What do I think of ML vs Lion? No big change..
One app I have been using a lot more than other mindmap apps is Simplemind, which works across the iMacs, iPhone 4, iPad 3, as well as my three active Android devices. Not the sexiest UI but most impressive interconnection via Dropbox.