The fundamental premise of this book is pretty good. The idea is as follows: You devote a given amount of time a day into work (say 10 hours). You earn an hourly wage, let's say for argument's sake it is $16 / hour. But there are many hidden costs associated with having a job.
For example, you may spend 30 min. commuting to and from work. After you get back from work, you may spend an additional hour "decompressing" - as in mindlessly watching TV in order to relax. You may also spend maybe another 30 min. or so talking about your work situation to your significant other.
So when you calculate your REAL hourly wages, you have to take all of this extra time into account. After all, you wouldn't be doing all of this stuff if you didn't work at this particular job.
Also, there are monetary costs to working. Such as spending money on nice work clothing. Buying lunch in the afternoon, because it would be too time consuming to prepare lunch every night. If there are things that you might do yourself but don't because of your job (taking care of your lawn, car, house, etc), you have to subtract the monetary costs of outsourcing all of this work.
What the book points out is that your REAL hourly wage is often much less than you think it is. In the example above, $16/hour could easily fall to $10 or $11/ hour.
The book then goes on to argue that when you start looking at stuff to buy - you should think about the cost of a new iPod for example in terms of hours spent working for it, not money. So for example, if you buy a $200 iPod, and you REAL hourly wage is $11/ hour, you've just spent about 18.2 hours of your life working away for that iPod. It really puts things into perspective.
The book does not tell you not to spend, but rather to be conscious of what you are actually spending, which is literally your life energy.
They have a "9 step program" but really it amounts to this:
1) Calculate your REAL net worth. All assets minus all debts. For many people its negative, because they have accumulated so much debt during their lifetime.
2) Become aware of your real hourly wage, and your spending patterns, and you will find that you naturally stop buying frivolous things. They recommend tracking EVERY single cent that you spend on goods. Pretty extreme, but I understand why. People in this program supposedly paid off seemingly large loads of debt in stunningly short time periods.
That's pretty much the gist of the book. The reason why I've given it 3.5 stars is because the manner in which this is all presented is not that great. The writing attempts to make the message seem very profound, when in fact it may not be so deep a truth as all that.
There is also a *LOT* of negative generalization about how everyone lives an over-stressed, under-paid lifestyle and it keeps coming up, over and over again in the book. It's this part that I really don't like. It probably all together takes up maybe 75 pages of the book, and it really only needs to be stated once. I think some brevity could have made this book really amazing, but it is still ok.
Finally, I strongly disagree with the investment chapter at the end of the book, and I think it will lead a lot of people astray. It recommends that you should only invest in long-term US treasury bonds that pay very marginal rates, because they are the only thing 100% guaranteed over time. A slightly "riskier" strategy is to invest in lifecycle funds.
Let me state plainly that to invest in only US treasury bonds would be akin to shooting yourself in the foot. Many things (like your job), are not 100% certain over long periods of time, and by using some common sense and effort you can do MUCH better than treasury bonds by making wise choices with index funds, stocks, bonds, and real estate.
Lifecycle funds are ok, but it is also perfectly ok to invest in stocks if you are willing to invest the time to do a little bit of research. "The Intelligent Investor" is the best book hands down for teaching you about stock selection and bonds, and I'd look there first if you are interested in learning about investing.
