@Sola0: Unfortunately you cannot please everyone. Even 5-star hotels receive the occassional "bad" guest. You have selected a strict cancellation policy so your guest will not receive any automatic refund. That leaves the ball square in your lap. The guest is probably going to leave a bad review if they honestly feel that your house was not up to their standards. However, you can also respond by stating that you understand the the house may not have been exactly what they were looking for and were happy to provide them with a refund for unused days. That will let future potential guest know that you are fair and honest. Of course, it is entirely up to you. If you'd rather not provide a refund then you have that option too and just as many hosts as say to give a refund would probably say not to give one too!
With all of that said, take the criticism constructively. Perhaps there are some things about the house that could be improved even though no one else has mentioned them yet. Is the fan loud? Are the beds in good shape? Are there things you can do to keep guests that are more picky happy? I'm not saying that you are doing anything wrong, just just saying to use this as an opportunity to take a step back and make sure that your house is truly the best it can be.
