I read "The Gold Mine" when it came out, and immediately had it added to our company Lean Library, and my own "read again" list.
It is definitely a must read for those that want to get into the depths of Lean, not just the tools. To get beyond and behind the mechanics of the tools, I group this book along with the outstanding Harvard Business Review articles: "The DNA of the Toyota Production System" by Spear & Bowen, and "Learning to Lead at Toyota" by Spear.
Understanding the mechanics of the Lean tools is necessary but not sufficient. Understanding the power behind the tools and the real challenge implementing them is critical. Tool books and true-life but superficial turnaround stories are helpful, but cannot reach the levels that a fictional story like this can (especially when told by authors who clearly "get it").
Here are specific thoughts on the book itself:
On the positives:
1) the descriptions of the dad character's interations with his sensei's were so realistic, I could picture myself with my own sensei's years ago (Hiyashi-san and Oba-san from Toyota and Matsubara-san from Tokai Rika). I found myself learning as much from remembering and rethinking what they said as I did from the book itself.
2) I was thoroughly impressed with the depth of understanding of Lean conveyed by the Balle's. The dad character hits on some real subtleties of Lean that it took me years of doing to even appreciate the power. I encourage readers to go over the 5S, 5 Why and TPM sections several times - the sections are brief, but there is some hard won wisdom in those passages.
3) the description of 5S on pages 120-126 is about the best I've seen anywhere (especially the often misunderstood 3rd and the rarely comprehended 4th and 5th).
4) The real dangers of a Lean transition are talked about in human terms with "real" people - the Materials Manager that couldn't make it, the production manager that did, the business partner that was focused on his relationship with the technical manager not the operation, and the change agent that gets burned out and recruited away. You just don't get that in the standard literature - the fictional story is much more effective.
On the wish list:
1) I wish the authors had set the story in a place without a "crisis". Getting across the "need to change" is somewhat easier (admittedly still difficult) when everyone knows there is an imminent crisis. It is harder to get a company with 20% margins to realize they could improve to 40% or to capture a larger market. I believe the Balle's have the capability to write the harder story of a business that just wants to move to a higher level without a crisis.
2) "The Gold Mine" shows the "Lean Way" to change an operation, and takes a few well aimed shots at regular consultants. I wish they had taken a few more at the mythical search for "the" bottleneck espoused by another famous fictional turnaround story (see pages 46-47). The Balle's insight and storytelling ability might have been able to give us Lean disciples some more help in the Lean vs TOC debates. As it is, they left it hanging.
3) I wish more of the story took place at the plant (in Gemba). The point still gets made in the book, but changes happen in Gemba, not on the consultant's boat. I understand the character's frustrations, but was somewhat dissapointed and saddened by the lack of passion for manufacturing and the desire to "get in there".
4) I wish there was more dialogue with and from the actual operators. The characters talk about them, but the only real interactions with them take place at the stamping presses late in the book.
On the nitpicky side:
1) some typos got through editing that should have been caught - in a couple of places they were confusing, in others, just annoying.
2) I could have done without the son's personal life issues. I don't think they added much to the story and I found myself wanting to skip ahead, but afraid I'd miss something...