The book is not terribly long, but it really has no reason to exist as a book at all. Everything it says could be written just as well as a blog post.
Here's the content:
- innovations are "sustaining" (targeted at same markets) or "disruptive" (targeted initially at different markets, usually smaller lower margin markets) - it's not clear at all how slightly smaller disks were somehow inherently "disruptive", like 3.5 to 2.5 inch, I'm not even talking SSDs or anything crazy like that
- there's huge first mover advantage for "disruptive" innovations (claim backed by absolutely nothing in the book, or real world)
- existing corporations have trouble targeting "disruptive" markets (claim backed by a few anecdotes)
- setting up independent organization within company is not just the best, but basically the only way to deal with "disruptive" innovations (claim backed by a few anecdotes, strangely book also includes a few anecdotes to contrary, then tries to handwave them)
- disk drive industry is totally 100% representative of all industries, so anecdotes from it are basically natural laws
I'm not sure how true book's claim is. It's an interesting and coherent point of view, and it could have some degree of validity to it, but it's not argued terribly convincingly, and I can come up with a lot of anecdotes on both sides of all the subclaims.
tl;dr 2/5 The author should adopt disruptive innovation of blog posts, instead of trying to stick to dying book publishing industry.