I have followed that diet with great success for nearly 10 years. The history of the blood types was fascinating.
Type O (my dad): the original people (hunter/gatherers)
Diet: red meat, nuts, berries, some fruits and vegetables/ few grains or dairy
Type A: the Mideast agricultural revolution (9000 BC)
Type B (the rest of my family) : the steppe dwellers, Mongols
Diet: high in dairy, some meat (rabbit, venison, some fish), very tolerant to all food types
Type AB: recent development (1000AD)
Diet: very resticted due to A and B intolerances
The foods prohibited to all groups are pork, shell fish, peanuts and tomatoes.
I also recommend "In the Zone" about how each meal and snack should be a certain ratio of carb/protein/fat and the book "Adrenal Fatigue" about how outside stress factors (bad relationships) could be a more important factor than your diet on your health.