I'm not familiar with Dr. Sarno personally, but I am familiar with New York's PM&R scene. I'd be mildly skeptical about things coming out of there. Not very skeptical, they're excellent doctors, but there's a strong strain of very-alternative medicine running in that particular sub-culture.

On the other hand, if you want a really mind-expanding read about the fuzzier edges of medicine, you might want to read Daniel Moerman's "Meaning, Medicine, and the 'Placebo Effect'." Don't let down your skeptical guard, but it's worth a read.