I know some authors have said getting a nice and polite rejection is aggravating. This must be what they're talking about:
"It was well received here, but after some thought we have decided not to accept it for publication. I love the atmosphere and historical detail, but the story as a whole doesn't work for me. It never develops sufficient conflict or tension for an action-oriented story. I hope you'll consider us again, and I wish you the best success in placing this story elsewhere."