AngelList is the real deal. I've heard quite a few people having some success there. Even as a YC company, there is a startling hole after Demo Day... It can take months to close a round (it took us 5ish), even loaded down with Demo Day biz cards and meeting invites. If I were doing YC again today, I'd try to get on AngelList right after Demo Day...
I think AngelList is great. I haven't found funding yet but Nivi has been extremely helpful and led to several introductions already.
Nothing but great things to say about AngelList. I applied with my startup and while we weren't selected for that week, Nivi sent me a nice personalized email and has been super friendly and always open to chat about startups.
Dave Lifson, a Postling founder, describes the process from his point of view: