As a complete newbie to SSAS I found this really helpful.
I read it cover to cover over the space of 4 days and certainly feel massively more informed on the topic now.
Only criticisms I have are that the Understanding MDX chapter was pretty tough going and I feel should have had better explanations also a couple of sections in chapter 17 are baffling and I can only assume the wrong code snippets were printed (pages 788 and 794)
The problem with the book is it uses the generic Adventure Works Database. This changes regularly and as a hardly any of the examples and practices work. I changed some things to get it going but really its poor not to supply a database with the book. Given up after 7%