I like the Fridge, it seems fairly solid, simple to use, and fun. But there are two main problems with it:
1) Getting friends etc. to buy in. Until I do, I'm suffering from the ghost town problem.
2) There isn't a compelling use-case for me. Sure I'd like to get my family using it, except more and more of them are on Facebook and are fine using it. I don't have a compelling argument to get us to switch to Fridge (or some other smaller social network.)
I would try to get my workplace on it, but even then we're all friends on Facebook so what's the point?
I want to use it, I like it, I like the control it gives me, but I am struggling with the why and how.