Yes, I've read it - it was a long time ago I gave up smoking (15 years now), but I bought the book and I remember finding it quite helpful at the time. I didn't go to any of his clinics or anything though.
IIRC, he had a refreshingly straightforward style. I don't remember it as feeling like hypnosis - but then I wasn't at all into critical thinking at the time and there may well be nuances in it which I missed.
The bit which has stayed with me ever since is his thesis that you mustn't think of it as "giving up" - there is nothing worth having in smoking to give up, only something undesirable to stop and then lots of things to gain. He also gave an effective layman's explanation of what addiction is all about, which certainly struck a chord in me.
He also suggested stashing the money you would have spent of fags each week, and buying yourself other treats with it. I did this, and remember being very impressed with the amount of money which I accumulated over the course of a few months!
I wouldn't give Allen Carr sole credit for my personal victory over tobacco, though. At the time I was trying to impress a young lady who was a non-smoker (successfully as it turned out 8) ), so I had a powerful incentive of the kind you can't buy from Waterstone's.
So, it helped me. OTOH, I passed the book on to my sister, but it did nothing for her. All these years later, and she's still on about 30 a day
Ginger - very best wishes if you decide to try and quit smoking. It is soooo worth it! :)
IMNSHO, if a person doesn't really, really want to stop, deep in their heart of hearts, then no book in the world is going to convince them to do so. If you do really want to stop, then this book might help to get you through the bad times. Encouragement from friends is important too