I have recently read the book twice within a month (I borrowed it from the local library but it's on my Amazon wish list) and was blown away by it. I haven't read a comic for years - probably not since I was in my early teens (too many years ago to work out) - but this book was everything a book should be but in graphic novel form. Extremely well drawn and incredibly well written. Intelligent use of language; great plot and great characters. While the story is similar to the film version once you have read the book you realise how much has been changed. I'm past getting too upset over films not following the book as closely as I'd prefer and have long since forgiven Peter Jackson for some major changes to Lord of The Rings. Similarly I'll forgive the Wachowski brothers and James McTeigue for cutting out swathes of the book and changing the story-line to fit 120 minutes or so. However once you have read the book you'll realise how much better the original version is. It makes more sense and while leaving one or two things hanging it feels right.
Warning - just because it's in comic format it doesn't mean it's a child's book. I'd say 12 or over and that would depend on the child's maturity.