Yeh.. I have the first one.. Which number do you have?
I've heard that the the second and the third book are a bit more useful or something.

Steve Vai and John Petrucci have both studied in Berklee's university and because that's a university for electric guitar players or something like that I have no doubt that they wouldn't have practiced the book series over and around..

So, you can see, practice the whole serie and be as good as Vai.. Or something.. Duh.. :)