I haven't read that book, but his other one - Taking care of behaviour.
Now, assuming that he hasn't changed his opinion too much between the two books, I actually think that most of his ideas are pretty good and have seen a few gifted colleagues use the same principles - conciously and unconsciousy - in secondary classrooms, with huge successes.
In Taking care of behaviour he talks a lot about the need for positive relationships with students, being visibly bothered about them as humans and treating them with respect, BUT he also points out the need for sanctions. The difference lies in the delivery.
Yes, you can take some of his ideas to the extreme - I would not start shaking everyone's hands (goodness knows where they've been) - but the general principle behind what he says is true and always has been. Detentions don't work and create resentment on both sides and you do get people to work with you better when you create a positive environment.
It works for adults, too - I have left a few very toxic schools with resentful staff who did the minimum and worked in schools where the loyalty of staff to the head meant that they went the extra mile.
A colleague got students we both taught to eat out of his hands while I really struggled to teach the same bunch of students. I asked him why there was such a massive difference in how they behaved for the two of us and it really was only down to the relationships he had built with them and his positive nature.
He doesn't advocate giving chances over and over again beyond what we are expected to do anyway - fresh start every lesson etc. He does, though, recognise that a punitive system doesn't work.
Decent managers use the same principle of relentless positivity to get their staff to work harder. No one works their best out of fear of punishment.