Having read an introductory book on poker, it seemed time to read something with a bit more of an in-depth look at the theory (although I haven't actually played the game properly yet!). I wasn't sure what to expect. Perhaps big tables of probabilities, or detailed guides of what to do in particular situations?
As it turns out, it's not what I expected. There is very little devoted to any particular game, and I think I saw one small table of probabilities, only meant as an example. In fact, this book is really a toolkit of concepts to apply to the analysis of variations of poker. It seems to assume a certain amount of poker experience and the ability to work out basic probabilities for yourself, and then adds a neato arsenal of techniques on top.
What I found quite interesting is that the whole book is about probability and game theory, but presented in a non-mathematical form. I had to take a few of the rules of thumb away, and convert them into algebra before I believed them, but they seem to hold true. Strict game theory in the simple cases give way to rules of thumb with a logical argument in the complex cases. Bayes theorem is mentioned in passing. While I can't vouch for the practicality of it, it's solid theory.