I like the straight-forward nature of the three "rules" for dealing with sibling conflicts, and agree that no good ever comes from taking sides in arguments between my kids. I find his "Stop it, you two!" (or in my case, "you three!")to be one of the greatest parenting phrases I've learned. However, a lot of his examples seem to end with a child, upon figuring out that his parent won't intervene on his behalf, declaring his plan for revenge as he leaves the room. For example, one of his recurring themes is a kid tattling on his sibling for swearing at him. Parent gives sympathy but refuses to get involved and in the end, the kid leaves saying, "Fine, then I'm going to call him a worse swear." This is the point that I think most parents, myself included, would have a difficult time not jumping in and saying something about his plan to go swear at his brother. I get that letting him go at that point is part of the whole "don't get involved" and "let them learn from experience" rules, but it doesn't feel right to me to not help the child think of some other alternatives or at least help the kid cool down so that he's not as inclined to just go back in fighting. This doesn't mean you have to say something like, "You do that, mister, and you're grounded!" but you could say, "You think that will help?" Or, "What, like Giant Ugly Cabbage Head?" (or something equally ridiculous to get him laughing). Or "I wonder if you can think of a swear so horrible it will make him fall on his knees and say, 'Oh brother, I'm soooooo sorry I ever swore at you. I'll never ever do it again and you can have all my best xbox games forever if you'll just forgive me...'" (give him what he wants in fantasy, if not reality).
I guess I believe that a parent can help defuse a child's anger without taking sides and while that does pull you into the argument more than this author seems to suggest is necessary, I think it's a pretty important role for a parent to play.
So, would I suggest reading the book? Yes, but perhaps in tandem with another book like Siblings Without Rivalry: How to Help Your Children Live Together So You Can Live Too or Playful Parenting so you have some ideas about what to say to a child who has just told you his plans for revenge.