GlennH stated it perfectly "My advice to anyone taking it would be to study a mile wide and an inch deep. There's not gonna be any astro-physics on there, but theres something about everything."
I didn't spend a lot of time studying, I just skimmed through Pearson's 7th Ed. I did take 2 practice exams the day before I went in for the ASTB. My emphasis was internalizing the clock during the practice sessions so I had a good idea how I was doing with time as I took the exam for real. On each practice I was getting about 80% correct, but was also consistently finishing each section with 1-3 minutes to spare. Pearson's tells you exactly how much time you will have to complete each section. After each section was complete (during my practice sessions), I would take a (timed) two-minute break. I found this routine to be very beneficial when I took the ASTB several months ago.
I scored 6/7/7, 54 on my one and only attempt. I know for certain three questions that I missed. All for the same reason, I mixed up my numbers. I pulled my application before October 2009 boards and will be submitting them within the next two weeks to hit February boards. From what I have heard, my scores won't even be close unless you have a great GPA in a respectable major.
Although the Navy claims to "Look at the applicant as a whole, and no single factor (assuming you pass your physical) will qualify nor disqualify an applicant" the fact is that they don't. One factor can absolutely prevent your application from even being looked at.
So make sure your package is as close to perfect as you can.
He also suggested I'd be better off if I would add one or two more letters of recommendation. This was knowing I already had letters from the following: O-1, O-5, O-6, O-10. The O-10 was a fixed-wing military pilot for 35 of 46 years as an officer.
Good luck to everybody. I hope to see y'all in Newport in April.