This book is written in a very clear and matter-of-fact style. We get lots of facts and details, and we usually get pretty up-front descriptions. Ever wonder what a little girl buys at the supermarket? Don't worry, Neil Gaiman is happy to tell us:
[Coraline] opened her money box and walked down to the supermarket. She bought two large bottles of limeade, a chocolate cake, and a new bag of apples, and went back home and ate them for dinner. (5.18)
It makes sense that we'd get so many clear descriptions and details about things: Neil Gaiman clearly wants us to freak out alongside Coraline, and knowing exactly what she's doing and seeing makes this possible.
Coraline also builds suspense by being succinct: that means it's not too wordy. In terms of writing style, we get lots of short sentences and fairly small words.
"What's it for?" asked Coraline. The hole went all the way through the middle of the stone. She held it up to the window and looked through it. (2.79)
This type of style also reflects the fact that the star of this story is a child. Coraline herself thinks and speaks in fairly simple sentences; after all, she is a kid and she tends to be pretty to-the-point with things. But this isn't to say that Coraline isn't smart – far from it, actually. She has a pretty advanced vocabulary and her speaking style often reveals how clever and smart she really is:
"I think my other mother has them both in her clutches. She may want to keep them [...] or she may simply have them in order to lure me back into reach of her fingers. I'm not sure." (5.49)
This story includes a lot of Coraline's thoughts, and the narrator chimes in with some reflections, too. As a result, the style can get a little poetic sometimes.
Someone had once told her that if you look up at the sky from the bottom of a mine shaft, even in the brightest daylight, you see a night sky and stars. Coraline wondered if the hand could see stars from where it was. (13.71)
Our thoughts are sometimes more poetic than the words we actually get to say aloud. By recording Coraline's thoughts, then, Gaiman affects the style of his whole book.