I'm an avid reader...not only that, every book I read I take time to review, because as an author myself I know how important they are. A positive review is like an injection of encouragement, the push needed sometimes to keep us going.
Even a negative review is welcome, because it shows someone who read our book has taken the time to express their thoughts about it. Even with a negative review there are things that can be learned, helping us perhaps to see things from the readers point of view. All input is valuable...unless of course it is vicious and merely seeking to cause hurt.
I struggle to understand why someone can't take a few minutes to write a few words about a book they've read. After all a review on Amazon only has to be a little over twenty words, so not much to ask.
Reviews are an important aid in finding a good book to read. I personally find them invaluable. When I'm interested in a certain book I scan the reviews to give me an idea as to whether it's the sort of genre I'll enjoy, and if the content is the sort of thing I would read; as I don't like overt sex, violence, or bad language in the books I read. So you can see how a review would be helpful to me.
Nevertheless, more than anything, we authors badly need reviews, need the encouragement. It's so good to hear that someone you don't know, and may never meet has read and enjoyed a book you have written...it's awesome!
Gripe over. I have a book to finish and a review to write!