There are lots of very good, very long GMAT guides out there -- this is not one of them. Outsmarting the GMAT is a short ebook that is meant to complement all those guides you bought and those classes you paid for. It's a short guide that's designed to get understandable, practical tips straight to you, without any wasted time or unnecessary information. This book is designed to be read in a hour or two, during which you'll pick up valuable tips and organize your thoughts about how you want to beat this test.
This guide works for people who are new to the test and want some GMAT tips to help them gets started, as well as people who are just days (or even hours) away from the test and want some last-minute ideas on how to polish their score. This isn't the guide that's going to get you from a 500 to a 700, it's designed to help you beat your maximum score and achieve your potential without weeks and weeks of agony.
Ultimately, the GMAT is just a small step on the road to your MBA and it's a test for which you can -- and should -- optimize your studying. This means getting in the right mindset to identify what you need from the test and then to study for that. This also may not mean shooting for an 800, but rather focusing on where you can glean points and how to achieve your best score possible.