I not only read book reviews, but I write them for other authors as well. I read a lot and always leave a review on Amazon and Goodreads if I have time. I have also written a nonfiction book called, How to Write a Simple Book Review, which helps readers to understand that a review, positive or negative can be helpful to writers. A negative review does not mean being nasty, it just gives you chance to tell the author what they could have done t make the book better. So fo me a bad review is always helpful and I always tell other authors that you cannot expect every reader to like our book, but if the reviews slate the editing or formatting then do something about it.