Coraline is a children's book in a lot of ways: it stars a child, it has short chapters, and it uses pretty simple language. But Coraline is one of those amazing books that can be read by anyone at any age, because the plot is really engaging (and even scary) for people of all ages. This book is an easy and fast read for older folks, but it's very accessible (or easy-to-understand) for those of us who are a bit younger.
But don't let the easy aspects of Coraline fool you. The book has a lot of really meaningful themes and deep ideas in it. You might want to slow down to read this book carefully so you can catch everything Neil Gaiman put into it.