What do you know about Zonkk?

A few weeks ago I asked what you knew about GROU.PS; today I am seeking feedback on Zonkk.  Has anyone given it a try?  What do you think?  Positives/negatives?

As I mentioned before, I am looking at migrating the MS support group social network (currently with Ning)  that I lead and need to keep it as clean and as simple as possible.  Thanks so much!!