I met Christian Bolton a number of years ago when I done a course with him at Microsoft under a Premier Contract and knew from that how much he knew about the depths of SQL Server, and this book shows that this is still the case, along with his co-authors.
It is clearly laid out and the authors have written in a style that makes it easy reading - unlike other technical books which can be (very) dry and can only really used as a reference. It dives in deep into the internals of SQL Server without overwhelming you and gives real world examples on how the knowledge did (or could have) resolved an issue. It also covers all areas related to SQL Server, from the network and storage through to the actual processor architecture and operating system you will be using.
There are areas that will be of use to developers (indexes/tuning etc) that would help them to understand the challenges of operational systems but I would say that this is aimed directly at the Production DBA whose neck is on the line. If this is you - make this your top book - get it, read it, re-read it, and keep it to hand because it will help you out one day
My only gripe with the book is that it is so good I could loose work....