Yes, the book is suffecient to prep for the exam. But you will also have to practice with SQL Queries in SSMS.

For people working with TSQL and 5-10 yrs of work-x you just need to know the new stuff been introduced in SQL 2012, that's it. The whole exam is just on Querying the Database tables, that's it.

For exam details and on what to prepare for 70-461 Exam check the following blog post:

Link:http://sqlwithmanoj.wordpress.com/2012/11/16/passed-70-461-exam-querying-microsoft-sql-server-2012/[/url]