Before the film, there was the graphic novel. Of course, before the graphic novel, there was the book. I made a conscious decision - because I'm awkward like that - to read the graphic novel before any of them, because I like the medium and I associate Neil Gaiman with the graphic art medium. It's such a good and unusual story, I slightly regret doing that now - as although the artwork in this book is of very high standard, I think using my imagination as I read the novel would have been more of a personal experience.
Having said that, if you have read the book or seen the film, there is much to be gained from reading it in this form. The artwork is scary, though drawn so that the scares are understated. Though the story might frighten younger readers, you get the feeling that some of the artwork is held back - kept light where it could have been dark. Having said that, the "other Mother" is a genuinely scary sight at times and having her as the scariest thing in the book is probably the right call.
At 186 pages it's long enough to absorb yourself in and still complete it in a couple of sittings, or take it on in one extended readthrough.