One who makes a practice of passing written judgement on books would do well to reveal at least some of the background and prejudices that go into those judgements, so I will make a brief attempt at so doing. Whether or not I like a book is determined by many factors, not all of which I know myself.
I'm a writer—if you can say that of one whose paid, professional writing experiences ended several decades ago—so I like well-written books. I like good grammar, correct spelling, and well-organized paragraphs. I like coherent ideas presented logically and accurately.
I'm reasonably intelligent and well-educated, so I do not like being talked down to. I don't like books that assume I have the vocabulary and attention span of an average fourth grader. I especially don't like folksy books that sound like conversation. That's great for blogs, Facebook, and Twitter, but if an idea is worth putting ink to paper, it's worth a more serious, careful treatment.I'm a human being, so books that ring true to my own experiences and beliefs will be more positively and enthusiastically received than those that do not. By that I do not mean that I only want to hear what I already know, or never to be challenged by new ideas and approaches, but that the new data should fit in with all I have thus far learned of reality. I love trying to fit the next piece into a jigsaw puzzle of the Grand Canyon, but not if the image on the piece is part of the Empire State Building.
Books that teach, enlighten, and inspire me are more likely to get positive reviews, whether they are non-fiction or imaginative. Dark, depressing books are likely to get panned unless they are really, really good in other ways. In fact, if I had to choose one criterion for judgement, it would be the effect the book has on my soul. Depressing books are worse than unworthy of the time spent reading them. I don't mean that books must always be upbeat, and ignore the sad, alarming, and darker parts of life, but if they don't offer hope and encourage positive action, they only contribute to the plague. On the other hand, a book that provides a glimpse of what is good, true, and beautiful, and inspires readers to seek and find and toil for that reality—such a book is a treasure indeed.
Bottom line, as simplistic as it may be: If a book makes me want to become a better person, I like it. If not, I don't.