Plausible-sounding criticism of Randi’s One Million Dollar Paranormal Challenge?

I’m currently working on a chapter for the book on how supernatural claims can be scientifically investigated. I’m including a few paragraphs on James Randi and his One Million Dollar Paranormal Challenge (link is to Wikipedia). For obvious reasons, it would be nice to include a brief response to some criticisms of the challenge, but I’m not sure where to start. I’m worried a Google search will just return nuttiness.

The Wikipedia article’s discussion isn’t bad, and I may just track down the primary sources, write a quick summary, and call it a day. Or are there other points that would be more worth my time? Does anyone reading this have their own reservations about the challenge?

Bill O'Reilly's argument for the existence of God
Peter van Inwagen's argument for Christianity
Tweaking the "beta testing a book" project
Angry Atheists? chapter 8: Science and Religion II: Evolution