You may disagree. If you do I hope you'll tell me why. I would like to feel happier with it. If you want to check it out, that number again: http://www.orbooks.com/our-books/greenhouse.
I remember attending a SFWA workshop at one of the first cons I ever attended as a member, and having it explained to me that a cover is "a little billboard" that advertises in an arresting image what a book is about. The example was the cover of the mass-market edition of Jaws--little human swimmer centered on the horizontal line of the water's surface, gigantic maw rising vertically beneath her. Perfect. Imagine, then, my disappointment when not one of my own book covers came close to approximating that sort of graphic impact. Well, few covers do. But some come closer than others, and to me this cover would be more appropriate on a book of games and crossword puzzles.
Of course it's what's between the covers that matters. But O/R just sent me an email with a big image of the cover in it, and I was just thinking.