The first word that comes to mind to describe this book is "boring".
I cannot understand how it could have got so many 5 stars - people need to read more business books! If you want an excellent book on lean startups you MUST read The Startup Owner's Manual: The Step-By-Step Guide for Building a Great Company: 1
by Steve Blank. Do not waste your money on this book.
The book is nevertheless quite an interesting read in some parts, but unquestionably very over-rated and very padded out. The book may have something to offer about how to save time and costs when running a start up, but this has more to to with common sense than with the real concept of 'lean' as with 'lean manufacturing'.
Eric Ries tells us a lot about his experience as a CTO in a Silicon Valley startup and how they managed to dupe investors out of $millions before they all realised that to have a successful startup, you must start with the customer and try and define what customers' need or desire that you are going to satisfy. What Eric and his colleagues did was to essentially start by developing a very expensive Web product without really finding out if anyone actually wanted it. Anyone with any business education should have avoided the costly mistakes that they initially made. This book goes on to suggest various ways that could help you save time and money by not doing what they did. But, it is however very, very short on any detail.
The book is very much geared towards IT startups who lack the staff with a strong business education, particularly those IT startups who think they are going to be the next Facebook, or at least have $Ms to invest in the early stages. If you are thinking of setting up a new business in a more traditional line of business and you are based in somewhere like Truro or Bradford or Edinburgh in the UK, you will find this book of limited use.
Be aware that it is full of Americanisms and Silicon Valley-speak. To be honest this book really is not much use if you are thinking of setting up any business other than an IT/software product or service.