Why what? Why we are happy with it? It is easy to implement and the people creating it are smart. They've done a good job so far, I see no reason why it won't be successful in the future.

The browser integration will be amazing when its ready, but until then, it is the closest thing to FB auth without requiring FB or people to give up their friends list or other information they are concerned about.

I'm not sure what 'crucial component' you are talking about, but we are just using browserid.org.