This book is arguably one of the best Dr Who Books out there and there are a lot of them! If you are interested in Dr Who (if you aren't don't worry, there is help out there!, an interest in sc-fi/fantasy will do) then this book is essential for both the collector and/or casual reader.
The book as well as giving a very detailed account of the Daleks - Rank, Episode Guide, related stories - books and other media such as audio and computer games is a worthwhile read, the main problem is once you start, there may be a search party out for you as you will be completely drawn into the book.
As mentioned although the book is primarily a Dalek book, there is accounts of Davros, enemies, planets; notably Skaro their home land and a nostalgic look at comics and magazines from previous decades such as Dalek Specials and the Annuals.
The book is fairly recent, being published this year (2011) so is pretty up to date including the new daleks from the Matt Smith / Eleventh Doctor era.
At the end of the book is a chart showing all* the daleks from the 1960's to the present showing the evolution of the machines, and throughout the book is the development stage of certain types with proposed variations and designs - including the very first to the very last (so far)
* There is however no mention of the Red Dalek (Saucer Commander of the movie version) but that's the only fault, if you can call it that.
All in all a very informative and worthwhile book to get and as I said if you are a DR Who fan AND in particular the Daleks this is a No Questions Asked/No Brainer item for your collection