I want to get a couple GRE prep books before I take the exam. I've read some reviews on amazon, but I'd love to get the opinions of you all on them. TIA

I bought several and this is the one I ended up using the most:
http://www.amazon.com/Pass-Key-GRE-Test-Barrons/dp/0764117823/ref=pd_sim_b_img_4

Its paperback sized so I basically carried it around in my purse for a few months and tried to memorize a word or two every time I had a chance.
There is a nice list of math formulas which are great for brushing up and some strategy tips that I found very useful.

I would get the bigger books for practice tests which have better explanations but the Pass Key is great for quick reference and on days you don't have the patience to sit down and do exhaustive study.