This is possibly one of the best technical books I have ever read - I can't believe I have been taking a wage based on my skills as an Oracle developer considering the huge gaps in my knowlege that have been highlighted by this tome.
Usually I shy away from large technical volumes because I know from experience they just sit, gathering dust, on my bookshelves. However, this book is so well written it is actually like pleasure reading. If I did have a criticism it would be that the author really pushes his mantra of "do your own benchmarking", consequently every point he makes has lenghthy examples of tests he has run along side it. Sometimes it just makes you think, "OK, I believe you, now lets get on with it". This is a minor quibble, the book is a reference, not meant to be read from cover to cover (although I did) and also much can be learnt from just looking at the code he is writing.
If you have anything to do with Oracle in your working life, other than being the most low level user, you need to read this book.