What can we learn from iLike?

Since introducing its Facebook app, iLike has been growing like crazy (300,000 users per-DAY????... wow...). A lot of people obviously find this to be a very very very useful tool.

In ways, iLike is doing with music what we aim to do with blog content over at outbrain.

So I was wondering - what can we learn from them? If you like iLike (hmmm...) - what is it exactly that makes this app work so well for you? Why do you recommend it to others? Is the Facebook virality its main cause for success? Or would it be as successful independently?

I'd love to get any feedback you have on this subject in the comments. Thanks!