Last week I read an article, or something since I don't remember where or what it was, that said if what you hear at the end of your sermon is "that was interesting" then you haven't closed the loop. You have not told people what you expect them to take from the sermon and how to apply it to their lives.
Of course yesterday the first comment after I was done at my first church was that my sermon was "interesting." I'll be honest and say that it was not my best sermon by any means, and I knew that going into it. On Saturday my wife asked how it was, and I was brutally honest and said that it sucked. I think it preached a little better than it read, and it was better at my second church than the first, but it still wasn't great. But I did try and tweak it to try and close the loop, but I wasn't totally successful.
I will also say that just because someone says it was "interesting" does not mean that the sermon necessarily failed. I have sometimes found that people will say this not because they didn't think it applicable, but instead because they disagreed with what I had to say or it contradicted everything they had been taught their entire life, and therefore they are either still processing or have ignored it altogether. So this comment doesn't necessarily mean that I did a bad job, although perhaps I could have explained better or differently.
But whatever the reason given, "that was interesting" is not really good feedback for a preacher, because without more context on the givers part it doesn't communicate much information, the same as "I really enjoyed that" doesn't really tell me anything.
I did have one person post something on facebook about the sermon, and what she thought it was about was not what I would have said was the central focus, but she said it was about forgiveness and so I'm totally okay with that.