I would wait spit wad. Finish your book because i guarantee about 3/5ths of the exam will cover the same topics. the other 2/5ths will be new technology and new updates.
Finish your book, get another book to review the difference and read, then take the NEW exam.
It should also be noted the did away with the 'track' that allowed you to choose which exam to take. Now it is just two exams. The 600 level was two exams, but one of those you got to choose from three 'tracks'.
I probably won't take it until next year, my certification for the 600 level one i took last january is good until i believe 2010 from what the certification says.