I think a good cover and title are definitely the key to enticing readers to pick up your book in the first place. But from there on in, it's all about the story and the writing. A good cover and title may grab readers' interest initially. But if your story isn't great, or the execution of it is poor, then those readers may well put the book down before reaching the end. And they certainly won't return to purchase any future stories you write - regardless of how incredible the covers and titles are!
