The first thing a reader sees of a book is its cover, and the best covers give a hint of what genre the book is, and perhaps what sort of feel it will have: cosy or dark, violent or gentle, faery realms or everyday life.

That means the job of a cover designer (along with the cover illustrator, though in this case Nik is both) is to tell the reader a little something about what they'll find if they read the book. As readers, we can't help but jusdge a book by its cover, at least a little bit, so a cover that looks like it's going to be a fairytale love story that turns out to be on a book that's about overthrowing a facist government really hasn't done its job.

That said, many people have the impression that illustrated covers are for kids' books. A look at the history of book covers in general--especially science fiction, fantasy, and romance--will show that that's simply not true. Illustration is for everyone, though perhaps it could be argued that certain styles of illustration work better with some genres of fiction.