When selecting books to buy (a bit of an obsession with me), I pay some attention to Amazon reviews. I've found that the more useful reviews are those with 2, 3, or 4 stars. People rating books at the extremes (5, the highest review, or 1) often have biases, agendas, or serious personality disorders. Still, I do read a few of the 1-star reviews just to find out why people hate the book.
The Toyota Way, by Jeffrey Liker, is an excellent overview of the Toyota Production System (TPS). It takes a very positive stance on the value of the TPS, however, and does not go out of its way to critique things.
Out of 84 reviews, there are only four 1-star reviews of the book, a handful of 3-star reviews, and everything else is fours and fives. Three of four 1-star reviews complain that Liker paints a picture of the "old" Toyota. These reviewers have first-hand experience with the implementation of TPS at one of the Toyota plants. A quote from a negative review: "When Mr. Cho opened this plant back in 1988, we were a much better run organization and we earned many J.D. Power awards because the environment at that time was the application of many of these 14 Principles."
Thus even the small number of people who slammed the book see the value of of TPS, a specific implementation of lean principles. The reviewer recognized that current challenges were caused by moving away from the process's principles. It is much the same with agile, which at its heart is a lean process. The principles of the TPS and the principles of agile are solid. Failures in agile or lean are usually caused when the application (or lack of application) of specific practices is not reconcilable with the principles.
That's not to say that TPS or agile processes don't create challenges. Indeed, the processes themselves introduce problems that would not exist otherwise. (For example, the core notion of "iterate and increment" in agile can far more rapidly degrade a system's design if proper controls don't exist.) There are always tradeoffs!
The core principle underlying the TPS is that the "right process will produce the right results." This message underlies one of our largest schisms in the software development community today. During a fairly intense series of blog debates involving Bob Martin, Jeff Atwood, and Joel Spolsky, Atwood posted, "If you're not careful, you might even slip and fall into a Methodology. Then you're in real trouble."
Toyota asks their workers to use their heads, to look for continual improvement (kaizen), as part of the TPS process. So does Uncle Bob. Atwood and Spolsky also say to use your head--but eschew process. Notably, Toyota quality has suffered in the past few years, as our Amazon reviewer also indicates. Yet Toyota will stick to its guns with TPS. The process and its principles are not the problem. In fact, the process lays the foundation for best opportunities to understand what's wrong with its implementation.