I've not used it as an owner, but it seems to be a very good solution for those who want free software that you don't even have to host. I mean, like ProBoards or Forumotion, there is no fee to use it, though there are upgrades where you can use your own domain. Is that also true for Jcink? I'm not sure.
Anyway, I don't think any solution like this is good enough for me, though. I need full control as with a free solution like phpBB or a paid one like XenForo. It allows me freedom to do more options.