Yes, I do and have done so for over 10 years now. It made an enormous difference to my gut health - IBS disappeared, acid reflux is minimised and I no longer feel nauseous after 50-66% of my meals. Brain fade and fatigue straight after lunch diminished a lot as well.
I follow it pretty closely; and thank God that I am a group B and can still have dairy with impunity! I found that, although refined wheat was suggested as a "neutral" for me, giving it up entirely was a far better plan. I can have a small amount very occasionally without incidence, but not more than once - if I do it twice in a short space of time, then I suffer.
I have to say I read the book in a spirit of complete scepticism - being a blood scientist - but things rang bells for me, and so I tried it and was amazed at the result. I still think some of the science in it is a bit off; the anthropology is a bit hit and miss, for e.g.! But the lectins - well yes. I have no issue with the science there. There have been some sceptics who have tried to refute the whole thing on the basis that lectins are proteins and therefore will be digested in the stomach and never make it as far as the blood; but this is rubbish. Lectins are pretty resistant to digestion and some are known to cause problems - ricin, for example (a lectin from the castor oil plant) is a highly potent toxin that can kill people; the lectins from kidney beans (unsoaked) are pretty dangerous too, and those from the fava bean can cause a disease condition known as "favism". So - there is something in it, I believe.
A friend of mine who is a group A tried it - and lost the persistent 2st overweight that she had found unshiftable.
I can't say it's had a positive impact on my weight, possibly the opposite as the IBS diminished - but I don't blame the diet itself for that, just my eating habits!
However, the change in my digestive health is so immense that I work around the diet all the time - and despite DH being pissed off occasionally and asking me if I'll ever "grow out of it"
we cope well as a family.