Mark and I went and saw this today. Really good movie, I was surprised by how faithful it was to the book. Mark enjoyed it too, which surprised me a bit because it is a little long and kind of drags some in the beginning; but that's just so that they can fully develop all of the characters.
One word of warning, this movie is NOT FOR KIDS! DO NOT TAKE YOUR CHILDREN TO SEE THIS MOVIE EVEN THOUGH IT IS ABOUT COMIC BOOK SUPER HEROES! Brutal graphic-violence, more than one explicit sex scene (including a partial rape scene), foul language, nudity to include full frontal male nudity (he's a computer generated character, but you can still see his wiener), lesbian kissing, and a very morally ambiguous ending.
So, this is not going to be like Spider-Man where you can watch the movie with your kids and then go to McDonalds to buy the Happy Meal toys. It's rated R for a reason.
Regardless, I would highly recommend this movie to anyone over 18. It's one of those films that, after it's over, will make you think "What would I do in that situation? Would I make the same choices? Would I stick to my values, if doing so guaranteed my destruction?"
As far as I could tell, Rorschach was a perfect translation from the comic book character to the big screen.