I don't want to say this, because you will moan and groan when I do, but please don't judge a book by its cover. The only way to discover how good or bad a book is, is to read the words the author has written.
Book publishers need to make money and they use a lot of hype to convince you to BUY the product. I have no problem with this, as great authors deserve the rewards from writing great books, as do those who publish and promote them.
But all this hype can confuse matters and distort our expectations about a book. You can easily form an opinion of a book based on the over-informative blurb on the back, or the cool artwork on the cover, or the gushing 'shoutlines' by the media and other authors, or even the introduction by some fawning expert or fan.
But I suggest you ignore all that and simply start reading the book. You may really hate it, but at least your opinion is based on the author's words rather than the publisher's hype.