I always like to know what my readers think of what I am doing. I have had many who simply write they like a story. I've had readers write to my email or even pm when they feel a story is wrong or they just don't like it. Whether a reader loves or hates my story, the feed back is nice. However there are things in a review that help.
"I just love your story. It was so great." While nice it doesn't help me focus on whatever appealed to the reader this time. Was it the right balance of show and tell, the way the story flowed, or the simple lack of mistakes (for which my beta and editor teams have my gratitude for making it look as good as it does).
"This story really bugged me and I won't be reading any more of your work." Again this tells me I struck a nerve, but I have very little to go to attempt to improve my writing.
It is the reviewer who tells me how or why a story touched them or missed the mark that I love the most.
"I loved your poem about your grandmother. Reading it I couldn't help but think of my own and how she has touched my life. Thank you."
That fact that the reader loved my poem is nice but knowing I made it universal so the reader could relate to it shows me that I need to keep those details in my writing.
"I hated your story. You don't give enough details and I hated that you had no real ending."
I know I will never appeal to everyone, but the fact that I didn't have enough details is something concrete I can focus on. I can also look at the ending of the story and see if it is too open ended or not. Those comments, while negative, at least point me in the direction to improve my craft.