One thing I noticed is that I was trying to create a new article and I couldn't figure out the categories. Here is a video showing the issue I struggled with: http://screencast.com/t/o1p8SgH4E (in essence I couldn't figure out what to put in the categories box... I figured it wanted me to type in an existing category, but I didn't know what the existing categories were).
Perhaps it should/could be changed to a multi-select checkbox list, like this:
Just a thought, since not everyone is going to know what categories to pick from beforehand.
Thanks~!