Swapping books on Bookmooch

Has anyone ever heard of Bookmooch? It's a book-swapping website where you post books you want to get rid of and then browse for books you want. When you find a book you want you request it from the person who has it, who then sends it to you.

It's all totally free. You get points by posting books and by sending them to others, and then you use those points to get books from others. All you pay for is shipping when you send a book (and sending books is really cheap).

I signed up this weekend but haven't gotten any books yet. Someone actually has a Gladys Mitchell book which, according to Holt, are great mysteries and hard-to-find. The one this person has is called "Spotted Hemlock." I'm thinking it might be the first one I order. Anyone know if it is any good?

Unfortunately for me, the books I have posted are all relatively popular mysteries, which probably means not many people will want them.