I felt this book is one of the most awesome book of all the 7 books.
There are hell lot of secrets when compared to the other books . Especially the secret past of Lord Voldemort and the way Dumbledore unearths is mind crackling.
The ending of this book will really spoil the mood for a very long time .:(.
I really admire the way J.K.Rowling thinks and creates the plot .
I definitely recommend this book(of-course you need to read the other 5 books as well before starting this:P).