Having only found out about this graphic novel series about a month or so ago, I have since bought and read all 5 current volumes out and waiting on the 6th before the movie comes out. It is one the few movies that make me want to go to the theaters to see it, but will probably just wait till the Blu-Ray of it. From what I have seen from the trailers it sticks very close to the books, I mean very close, hairstyles, art style, and even many of the lines. Here is one of the latest trailers that I think explain it the best and for those who have read the books will see how close it is to them.
If you have not read them yet, check out
Amazon.com they have a great price on them, or if you cannot wait and have a Borders near you search online and there are 40% off coupons you can use for one item and it takes them down to cheaper than Amazon after tax. While you can only use them for one item, you can go back as many times, or if you are lucky some have a bundle of all 5 as a single item.