This IMO is a very well written and engaging book.
There is a lot of very well researched historical information about the development of the style of the beer and it also covers the modern re-birth of IPA.
Ingredients and production techniques are well explained and I'm sure that even the most experienced brewer can take something from this book to improve their processes and beers of this style. Or even just experiment for the sake of it

Great recipe section including historical beers from the 18th Century to modern day beers from Stone, DogFish Head, Thornbridge and the likes.
The only small criticism I would have is that the recipes are written for big commercial kit, so there is a fair bit of work involved converting hop percentages and fiddling about with IBU's and such if you want to try and brew these beers at home.....but I guess this is part of the fun for many.
Lots of water profiles are given too which I liked.
All in all a very good book that I would heartily recommend. I am sure I will be referring back to it a lot over years to come.