I really wanted to use it, but I gave up as soon as soon as I realized that Facebook is the only way to log in. Not everyone will trust your website, and requiring Facebook limits the number of users you will receive.
Yeah, I understand that. I've gone back and forth on it a bit. When I complete my vision for the site there's going to be a lot of fun features that depend on your social graph, so I decided it's worth it.
The one thing I tried to avoid was asking for too many permission. The site only asks for basic permissions + your email address.