Value of Tweetbook, the Facebook for Tweeters

Recently I was invited to join Tweetbook, a social media networking site for people who use Twitter. I think that Twitter itself is great for networking, but why was Tweetbook created? What sort of value does Tweetbook have for Tweeters as opposed to Twitter alone? Can't Tweeters just find each other on Facebook? Is it just a "wannabe" Facebook? Does anyone here use Tweetbook? What have your experiences with it been like? I know I have a lot of questions, but I want to know how others perceive and use this site and if I should keep my account or say good riddance. All viewpoints are welcome!