It's funny that the topic of this course came up as I received a copy of it for my birthday. (I am still young enough to have one!)
I have gone through the first 3 CDs in the course and honestly, I thought that I had pretty good pitch, but I do believe that it has improved significantly. The exercises that he talks about on the courses are very similar to ones that my piano teacher started me on when I was a kid. However, he takes them a step beyond that by incorporating relative pitch.
Would I recommend these to anyone? Not really, these are not overnight cures for bad pitch. It even states in the lesson that it takes a lot of time and patience to actually realize a benefit. Since time is too tight for me to sail through the CDs, I am taking my time and every chance I get I do the exercises.
One of my favorites is playing intervals and trying to sing both notes. (See previous posts from Mark H. about the frequencies associated with playing two notes.) I was amazed at how hard this was in the beginning, but now is much easier. If I don't get perfect pitch, at least I am learning to listen a lot better and curing some weaknesses.