I'm often leery of movies based on books, especially books I like. But when it comes down to it, if it has Neil Gaiman's name on it, I'm there.
When Coraline got underway, I realized I didn't remember the book that well, so I just went along for the ride. From what I could remember, though, the basic plot honors the original pretty well. The tone of the movie definitely dovetails nicely with that of the book. Though rated PG, Coraline's a bit intense for the younger crowd, although probably not much more so than classic Disney "kiddie" flicks like Sleeping Beauty and Snow White. For the most part, Coraline is more creepy than scary, though the last act does add a scare factor.
The 3-D technology used for Coraline is impressive. There's not much of things jumping out at the audience, as in My Bloody Valentine, which in my opinion was a more appropriate approach for a younger audience. The 3-D really brings you into the story, most notably in the tunnel transition between Coraline's real world and the Other world.
Overall, I found Coraline immensely entertaining and wonderfully produced. My kids enjoyed it, as well, though at 11 and 15 they're a bit older than the target audience.