I read this book cover to cover. I took all the chapter sample tests, and the Appendix test. Then I re-read the book. I took the 734 exam today and passed 96% (only missed 2 out of 51 questions). Clearly this book works.
The sample exam questions are so close to the actual test questions that, if you understand why a sample question is correct in this book, take all the sample questions and do well, I don't think it is possible to fail the 734.
I say this with several caveats. First, the book is filled with typos and a few serious factual errors. You should have your laptop open as you go through the book and read the DB2 9 and 9.5 Information Center to verify details. Second, the book completely glosses over some DB2 features such as the Administration Server, some details on DPF, or how to use db2pd effectively. Again, check the Internet and IBM Information Center for more information to fill out those gaps.
The Index and Table of Contents could be much better.
I would have liked the Appendix sample test to have had different questions than those used in the Chapter sample tests. At some point obviously the reader begins to memorize the test questions which skews the results for the final sample test, reducing its effectiveness as an assessment tool.
This is NOT a generic reference for how to be an effective DBA. This is a certification guide and will only help you pass the 734 test. The 734 is NOT a comprehensive test of what it takes to be a DB2 LUW DBA. In my opinion, IBM needs to develop a more detailed certification roadmap for DB2 database administrators. In particular there should be a separate certification exam for DPF/Data Warehouse/Balanced Infosphere administration.
You should consider passing the 734 only the beginning of wisdom. Follow this up with your own independent reading in the IBM Information Center and Redbooks.