This was my third time taking the test, and I felt the best coming out of it. I had no passage on rocks, and all I can say is that this physical sciences section was the easiest I've taken. It was very straightforward, and seemed to be testing whether or not you'd studied the material, rather than throwing some crazy passage at you and have you use completely new equations and do calculations you have no idea how to even approach. All I can say is there is such a huge variability between forms out there. Sometimes you may get screwed with a form you'll be terrible at (i.e me in September of 2008) or you'll take a PS form and do okay, as I feel I did yesterday. The point is to study everything and practice being able to do scientific notation and do basic math very quickly. There was stuff on my exam that I'd seen before on previous AAMCs, stuff that you would think "oh, the MCAT is more of a thinking test, you don't need to memorize this info about ________, they don't test like that anymore, it's all in the passage now," No. That's not necessarily true. You won't necessarily get screwed with awful passages in PS about harmonic dampening in car breaks.
A lot of stuff TBR went over in their chemistry books showed up on the actual test. The same material was covered in Kaplan and TPR, but TBR did a better job explaining it. TPR also had some easy tips on how to solve problems that helped me yesterday on the actual test in PS. If you study hard, known your material and then take practice tests, you will be rewarded. I started studying for the MCAT in May 2007 and I was getting a 24 on my practice tests. I had a lot of deficiencies in PS in content and in math ability. I took the test first in August 07 and voided, studied more, took it again in September and got a 26. I studied with TBR, but I didn't work on my math speed, didn't pace myself in VR or PS. I didn't even finish VR or PS, and I had to guess on multiple passages in both because I ran out of time.
Now, my third time studying for it I've managed to get 29-32s on my practice tests, with no section below an 8. I still may retake in June, but the point here for all those people reading this thread who haven't taken the test: Don't let SDN freak you out, study hard, practice, pace yourself, and you'll be rewarded. Maybe it won't happen as quickly as you hope, but it will happen if you keep at it.