I did the 70-461 exam last year and I found it hard (not difficult per se, just a lot to remember). It took me the better part of a year to go through that very same book (at night, after work). I've been writing & learning SQL since 2000 and I knew a lot of it already. In the end, I passed it with time to spare.
There is a lot in the course. I did my best to incorporate it into my everyday work. As an example, although I find UPDATE, DELETE and INSERT statements logically easier to work with than a MERGE, I tried using MERGE instead of the standard DML statements. I don't especially like it but after a week of it, it came reasonably quickly.
Likewise there are chapters that were new to me — XML (which is, in our company, normally the domain of the developers), Full-Text Search, synonyms, to name but a few.
There were also parts that I learnt anew and use every week — OUTPUT DELETED.*, rows & ranges in windowing functions for example as well as refreshing my knowledge on isolation levels. When you can explain ACID, dirty and phantom reads to a 10-year old and they understand you, you know that you understand isolation levels. Make yourself flash cards and test yourself on syntax (for example, all of the options available to GROUP BY or the windowing functions). If you have a 30-minute train-commute each day, you can use it profitably with these cards.
There are sample questions available from third-party companies and the Microsoft exams do take some getting used to. If you are feeling ambitious, you might also consider the 70-761 exam. It has a new features but the two look very similar. It shouldn't be too much more effort to get both.