The first four parts of this book are absolutely fascinating. It's an in depth look at the psychology of shopping and it is exactly what the title promises. Underhill's company gets paid to spy on people in stores and see what they're doing wrong and right. The gems in this book are the anecdotes and the specific revelations about how any obstacle you put in the way of a shopper drops your sales figures. Any way you can make life easier raises your sales. This all seems sort of obvious, but most people running the businesses don't think it through.
One example is the entry zone at the front of the store - you'd think that's a prime location for signage, deals, brochures, etc. But when you're headed through the door into the store you see almost nothing and stop for almost nothing, and then (in America) you tend to drift to the right and then you're 'in' the store. If you put a store directory just inside the door, nobody uses it. Move it back a bit so you can find it once you're into the store and suddenly it's heavily utilized. He has hard observational data for all these, so they're compelling in addition to being fascinating.
And of course all the bad examples are great fun to read (seniors crawling along floors trying to read labels on badly shelved medicine), as are the descriptions of how different groups shop (male vs female, old vs young, parents vs. single, etc.) The whole book is pretty much a commercial for Underhill's company, but it's still informative and fun reading.
Where the book falls down is at the end, where a chapter on the Internet is shoehorned in and a perfunctory shout out to each of Envirosell's worldwide branches is included.
Even though I think he's more right than wrong, the whole Internet chapter comes across as a confused old guy muttering about how he doesn't get that new fangled rock music. He complains about how many review sites there are, for instance, and has no idea how much it can transform the shopping experience (and not just be a poor supplement). Worse, the book's entire premise is mostly about how you need observational data of real customers because they'll always do things you don't expect (can't argue there), but he HAS no data on this topic, so it's just not compelling. I can't help but think the whole chapter is just in there because 'we need something about teh intertubes'.
The 'Come Fly With Me' chapter must be in here because he needs to professionally backscratch all his international partners. It's pretty much useless and turns a mild commercial into an infomercial.
If I sound too negative, please don't take it that way - I'm just trying to tell you why this isn't a five star book. You have 220 pages of 'awesome and can't put it down' book followed by 40 pages of 'what the hell am I doing reading this' slog, then another 30 pages of fairly decent reading. If you don't read those two chapters, it's a five star book!