I first tried the diet about 3 years ago. I was an O+ who had gotten extremely ill. I used chinese medicine and the Blood Type Diet to feel better than I had ever felt before. Even still, as I got better, I found it easy to fall off the wagon and eat things like wheat and corn or corn sweeteners.
People say it's a fad diet, but for me, it is the only diet that has addressed the particular strengths and weaknesses of my digestive system, and it is the only diet that can be demonstrably said (although the evidence is anecdotal) to affect my health in a definitely positive way.
I hope this is an active board, as I hope to share knowledge and info with more people who are doing this diet. The formal dadamo website forum is closed, so this is one of the places I've found.