This type of feedback (size, location, floor plan) is difficult to do much with as a seller. You likely aren't going to build an addition to your house, nor will you physically move the house, nor will you reconfigure the floor plan. Sometimes the feedback is just a mild objection to be overcome -- did you realize that the unfinished bonus room could be finished quite inexpensively (size) and that the new South East connector will make your commute quite short (location)? Oftentimes, however, if you receive feedback about size, location or floor plan there isn't much you can do about it as a seller.
I also, however, will hear the following types of feedback after a showing:
This type of feedback (price, condition, marketing) is completely in your control as a seller. Many buyers will not make an offer if they think your list price is too far from reality -- adjusting your pricing may be just what you need to either generate more showings, or have a chance of the showings turning into offers. I almost included AGE as a factor outside of a seller's control, but it's much more about condition -- how well has a property been maintained, and is it in top showing shape so that buyers don't feel overwhelmed by short-term cosmetic updates and long-term maintenance needs? Finally, if a house has not been marketed thoroughly and effectively, it will likely have a much longer "days on market" than other properties, worrying buyers that perhaps they shouldn't buy the home because nobody else has in the last ten months.