The book in general focuses a bit too much on Immunity Debugger and its Python features. This is pretty cool though, as I'm always thrilled to learn new things, but it leaves you nevertheless with some questions if you don't have those handy libraries available that come with Immunity Debugger. And sometimes a reverse engineer has to use what is available. I mainly bought the book in the hope that IDAPython will be discussed and indeed one chapter is dedicated to it.
The author knows what he's writing about, so all in all worth its money. Something for every reverse engineer's bookshelf.