It details (rather shamelessly) the various psychological techniques, and game design traps, employed to make people fork over money. While the Free-To-Play model is just a model, a tool, that can be used (or abused) depending on how developers see fit, right now the F2P model is mostly being abused.
Techniques like “…putting the consumer in a very uncomfortable position in the game and then offering to remove this “pain” in return for spending money”, are being used to get gullible teens (and adults) to pay real money for things they really shouldn’t be paying for.
And just because you understand how these psychological tricks work, doesn’t make you immune to them. That’s the danger.