I - almost - completely agree with the comprehensive review by Rainardi. This is a top SSAS book, and the two other top three books are those by Teo Lachev (SSAS 2005) and by Irina, Edward & Alexander (SSAS 2008). To be a little more precise, however, this should only by your "No. 2 SSAS Book". You need one of the others first, depending on which SSAS version you are using. That'll give you a comprehensive overview, and then this book has the potential to make you a full-blown professional. It should not be your first book, though, since the level required is (in many parts) quite sophisticated, and since coverage is incomplete and "biased" by experience of what has the most practical importance.
This SSAS 2008 book is superb. For me it is, by far, the most useful book on SSAS (the second being Irina, Edward & Alexander's SSAS 2008, and the third is Teo Lachev's). I learned a lot from this book. The book is invaluable to me because in the last 2 years I have been doing a lot of cube development and in doing so I have discovered and developed some techniques or methods. And that was exactly what they wrote: their experience in developing cubes, plus their opinions and tips. Chris Webb in SSAS world is an authoritative figure and I consider his SSAS skills to be one of the highest in the world, along the lines of Mosha Pasumansky, Deepak Puri, Edward Melomed and Darren Gosbell. Marco Russo is famous in SSAS world because of his Many-to-Many Revolution, one of the very first things I learned when I started doing cube development. Alberto Ferrari is SSAS expert (I learned from him that materialized ref dim can produce incorrect results, something that I experienced myself) and he's a speaker at Euro PASS 2009. So reading this book is like getting the experiences of 3 SSAS experts. A book which content is derived from books online, i.e. the 'how to do stuff', is not too useful for me, as I can read it in the BOL myself. But a book that contains 3 experts' experience and thoughts, that's invaluable. And that is what this book is. Being a writer myself (I wrote data warehousing book on SQL Server 2 years ago), I can understand why not many experts want to spend their precious time to sit down and write their experiences in a book. Because writing a technical book is tiring and the money is not great. So when an expert does it, grab that book and learn. And this time it's not only one but three!
This book is not for absolute beginners but I am amazed page after page to read answers about questions I asked myself without always finding the answer.
This is both deep and practical. I like the fact that it does not assume SSAS is the best answer to all problems. For instance, it does mention that SSAS is not that great for chart of accounts compared to some other products, or that you would be better off not relying exclusively on SSAS to solve your currency rates problems.
In my current project, for instance, our developers have problems handling Year To Date calculations (please don't laugh) and the answer to similar date related calculations is so clearly explained in this book.
I thoroughly enjoyed this reading and plan to go back to it regularly for priceless "how to" advice.
You may want to check this article as this is how I learned about this book and it might convince you whether or not it is for you (.....)
Warning. This book is not for beginners but for us, OLAP cube developer that have already several OLAP cubes (SSAS) projects in production environment and are now dealing with advance topics such as scalability, fast design, implementation and maintenance. I had the privilege of having Chris Webb (author) as my Microsoft Instructor here in Dublin, Ireland. I am very impress with his expertise using MDX query language. Chapter 3, Designing More Complex Dimensions, Chapter 9: Securing the Cube and Chapter 10 on Productionization are definitely my favorites. There is a good collection resources and tools for monitoring Cube Performance and Usage. A must read for serious Cube Developers, especially those facing scalability and complexity challenges.
This is one of the good books on the subject. It caters for every level(i.e. beginners, experts etc) of readers something to take. Some of the confusing aspects of SSAS has been explained neatly. I liked it as it served the purpose for me.