From a look around the website I'd agree with Pommie: skip it. If OG Popa's grasp of microcontrollers is anything like his (her?) grasp of English grammar*, then the book is a waste of money.
* - Note: the only reason I mention this is that the same site offers a book on English grammar, but the site itself and the examples from the books use terrible grammar with numerous and consistent mistakes. Based on what I see on that site I would not recommend any book by that author.
Torben