I took it last November and scored a 144 (98%) after studying for a week. I used the red NLN exam review guide and found it to be a huge help. The only area that I felt was lacking in the study guide was basic physics. There was a little bit in there, but I've never had a physics class so it wasn't enough--there were a lot of physics questions on the exam! I would recommend if you have time, is to review a Physics Made Easy book or similar. The other science that was covered was mostly biology, and some pretty basic chemistry. I think that this test is designed to be able to be taken out of high school, so there really isn't much A&P or Micro (if I remember correctly).
I also recommend that when you review, if you are crunched for time, is to spend less time reviewing the reading comprehension section. At this point, you either know it or you don't. Of course you should review to get a feel for the types of questions, but it's not like the vocabulary in the review book is going to be the same as on the test. That was for me personally, obviously if you feel that you need to spend time on it, then that's what you will do.
For the math section, I had to relearn how to do basic math without a calculator. Math is definitely not my strong subject. If you really spend time doing those problems over and over, and getting the steps down without a calculator, then you'll be okay. There are a lot of percentiles, decimals, and fraction questions. The study guide was great for showing how to work out these types of problems. There was not a lot of algebra. Definitely time yourself when you do the practice tests. Since you'll have to work out these problems by hand, it adds time. It seems a lot of people run out of time near the end of the math section. They'll give you scratch paper.
If your exam is computerized (I think it usually is), then you'll be able to flag questions to go back to at the end. I had about 10 math problems flagged and when I went back to them, I was able to answer them easily because I was looking at them fresh. You'll get your score at the end, and a brief explanation of the raw score and ranking percentile. Oh, and the exam is three hours, with a break in between each section.
The best thing to do, is the day before, don't try and cram all this stuff in. Relax, sleep well, and leave plenty early the day of the exam. I had loads of traffic the day of my exam, couldn't find the building, and showed up late :uhoh21:, but maybe the adreneline actually helped me out! Good luck to you!!!