For me, one of the best things about it was just how fresh it all felt. Compared to a standard web (un)conference where everyone knows their space, expertise and opinions, here lots (most?) of us were exploring stuff outside of our day job and business-as-usual. It was passionate and interesting and I felt completely out of my depth, which was was great.
So in 2009, less of the comfort zone stuff please, and more like this.