I can't comment on his engines, but some of his stuff was very good. However, he was very well known for being extremely 'clever' in the marketing department. ie; he spouted such a huge amount of bull5hit per product, that by the time you were half way through reading about how amazing it was, you'd buy it purely so that you wouldn't read any more
Some of his stuff was also just a huge rip-off. The most obvious example being the plastic bosh dump valves, that he bought for about £12 each, wrapped in tin foil, wrote a huge paragraph about, and sold for £200