I bought destroyer and i have all the material from the kaplan course that a friend had given me. I found much of it to be kinda useless in a sense. I used my old books. Read over concepts that i forgot or i was a little iffy on. Just make sure u kno the things u mess up on COLD. I ahvent taken the real thing yet but i was killing all the practice tests. and i keep reviewing wat i learned again and again until its branded into my brain lol. Dont just get the basic jist of a concept u need to really grasp it, look at all the formulas. They practically speak forthemselves. GLUCK.
If you don't know any of the material, Destroyer will be very hard to use at first. Destroyer is good once you know the basics and you want to really master the material. The questions are challenging, but if you can do them you are good for the DAT.
I would also suggest reading a the other threads which deal with what's good for the DAT.