Without doubt one of the coolest things about being an author is receiving reader feedback. Fortunately most of it is good! I guess people who don't like your book either (a) don't finish it or (b) just don't bother sending you a letter or email to tell you so.
It is such a wonderful feeling to know that something you have written has connected with a reader. After all that's your hope as you sit at the computer for months on end and craft your story. It's amazing how one little email, Facebook comment or best of all - a handwritten letter - can really boost your spirits.
As a reader I often wondered whether authors read their mail or appreciated it, now I know they definitely do and there is no such thing as too much feedback. It is all absolutely welcome.