Saw this Saturday morning as part of the "you get 4 hours with a baby, we get 4 hours without a baby" grandparent exchange program. I was a big fan of the original graphic novel and we had just listened to the audio book in May, so the apparent absence in the previews of anything that resembled the plot of the book left me worried. Still, I tried to shut out the portion of my brain that was familiar with the original work and went to enjoy the spectacle.
Good call. It was a well done, beautiful and fun movie. The only problem is that it hewed so closely to the book for most of the film (and who made that preview, anyway?) that the points where they diverged felt wrong. Not jarringly wrong, not "that's it I'm leaving" level wrong, but still wrong. If you haven't read the book (or haven't read it in a while) wait until after you see the film and you should have a great time. DeNiro is great, Pheiffer does some great evil and it's pretty as all hell.
The changes from the book fall into three categories.
1) we don't have space: some characters got condensed out, some scenes were removed, and the "18 years ago" backstory was seriously trimmed, but hey, they only had 130 minutes. The edits were well done and much as I liked some off the lost scenes and characters they were ones that the story could lose without any major damage.
2) wink wink, nudge nudge: I figure somewhere along the line this got greenlighted because a studio exec was told it could be made to feel like Princess Bride - the whole 'knowing fairy tale for adults" thing. So several bits were altered to make them funnier in that sense. That made the movie feel different from the book: not better or worse . Just different. I have no problems with that.
3) But we're Hollywood!: and these changes are the reasons why you should see the movie before reading the book. Several rather clever bits in the book get changed into major set pieces because Hollywood has to have those. The moral center of the story is altered - not unforgivably so - to better mach the standard tropes. Some of the subtlety is written out large to make sure no one misses it. This is not to say the set pieces are bad, because other than a little bit of the contemporary urge for overkill they're quite good - impressive, clever, fun to watch. It's just that these changes weren't needed except to make sure that Stardust looked enough like other previous successful fantasy films to mollify the studio. Of course, since some 80% of the movie is right out of the book and all the major plot points get hit I can't complain too much.
Just go read the book after you see the movie. Which implies that you should go see the movie. It's fun.