The Daily Grail website (paranormal news, mostly) had posted a large article about the JREF’s Million Dollar challenge, titled The Myth of the Million Dollar Challenge. The article is rather long (about 4000 words) and in it the author, Greg, discusses the challenge. He mostly argues about the success probability that Randi requires from the participants (about 1 to 1 million for the full 1 Million prize), which is way way above what is considered significant in science (1 to 20).
He also tells of several cases where Randi seemed to back up from a suggested challenge, when it seemed too risky for him. He also raises some legal issues, which are mentioned in the rules of the challenge, in which the participants will lose all right to their presentation in the challenge.
The article even got a response from Randi (though only in Randi’s own newsletter), to which Greg responds as well in an update to the article. Interesting read to anyone interested in the million dollar challenge.