What makes for a good cover?

When sifting through the ever-varying pile of poetry books on my desk, I wince at some of the covers, while others just seem to demand that I should dive in and start reading, so what makes for a good one?

Like so much in packaging and presentation, it's subjective. As I know from designing wine labels, everyone's taste is different, and one important point is to know your target audience. And then there's the question of balance: eye-catching but not garishly so, an attractive font but not over the top.

However, for me, perhaps the most pivotal point is how the cover images and design relate to the book's title. If they are disparate, that won't draw anybody in, while a simple physical reflection or depiction of the title doesn't bring much to the party either. My favourite covers are those that clearly fit within a publisher's house style and build on the idea of stablemates, complementing the title, hinting at the book's contents, enticing the reader along.

All of the above is on my mind when I consider the cover that Edwin Smet at Eyewear has designed for The Knives of Villalejo. Of course, I'm totally biased! What do you think...?