As others mentioned, the main habari/habari repo commit count is low because the main development doesn't happen there, but in a submodule'd repo, habari/system. The purpose of this is to allow you to easily fork the main repo to add your own plugins and themes to it, while the submodule continues to pull from the system repo. It's very beneficial from a maintenance standpoint.
I'm not sure how to explain the community. My involvement has been nothing but beneficial for me, and it has been a similar experience for the people I know the community has touched. Development has been reasonably continuous, as you can see here: http://www.ohloh.net/p/habari