Mike has been an inspiration for me ever since I was suggested one of his interviews on Youtube a while back. His logical approach to bodybuilding is a much needed respite from the modern state of the field where everyone is trying to sell you some miracle supplement or one size fits all training program. Although I'm skeptical that intense exercise for extremely short periods, such as 20 minutes, can yield the results needed for competing in Mr Olympia, I think his training program has merit and is worthy of further investigation. I do, however, believe Mentzer is correct about intensity being the key for muscle development.
In this set of interviews, Mentzer makes a number of thought-provoking points on how to train optimally. I highly recommend anyone with an interest in fitness and bodybuilding check out these interviews.