Would not buy it if I were you. I, too, had it all throughout my preparation but rarely used it. The questions are all really long and involved, the likes of which you're likely never to see on the MCAT (since 15 minutes per question isn't really practical). However, I WOULD recommend it as an aid for a physics or chemistry class, or if you're extraordinarily weak in a certain area and have oodles of time with which to work on 10-step problems.
If you feel you know the material pretty well, and if you've only got until August, I would stick with the standard review books and practice tests.