While I can't dispute the effectiveness of this (see my 3 year-old react when I say "three"!), it's almost too simplistic: the author tries to imply that nearly every behavior can be corrected by doing a 1-2-3 method. While that works well in a lot of situations, he doesn't tell you what to do when the child is in Target, screaming blood-curdling yells, in the middle of the store floor. And you can't pick up a kid in this condition (to drag them to a time-out location, for instance), when they purposely stiffen their bodies so they slip out of your grip. And let me tell you, "1-2-3" does NOT effect a kid in full-on hellion mode, whether a timeout is being threatened or losing a toy, fun trip somewhere, or whatever. So a little help about "what to do when X happens," would've been good (I don't expect him to anticipate the million situations you can be in, but every parent experiences the full-on tantrum where nothing works).
Other than that, it really does work quite a bit. He's right in the idea that you can't talk during the discipline (though I learned to explain what my daughter was doing wrong and what I wanted her to do before we got to 1-2-3). And tag-teaming by both parents is really critical in having this work its full effect. I just wish he'd have given more on "here's what you do in this situation" rather than introducing what some pediatricians call "bribery" (he pays his kids 25 cents per so many minutes to be quiet in the car on road trips--sounds good on tape, til you realize that yep, you're bribing your kids--something I do quite a bit HA, but something the child psych doctors complain about).
Definitely worth the investment, though, for controlling at least half of the problems you might have with discipline. And it's presented in an enjoyable, pleasant format that makes you forget you're listening to a self-help tape (I listened to them all within a few days while running errands). Lastly, you'll feel better learning that every other parent out there has the same problems and challenges in child rearing that you have. Good buy.