I stayed three nights at Sara's apartment by myself and could not have been any happier with this apartment. It was spacious (I was just one person, but this would be good for like a small group of 3/4 people too) and clean and really quite perfect for me. It's in a nice, very safe neighborhood, and is within walking distance to all of the major tourist sites in Prague and right across the street from a shopping mall. I also arranged to get picked up by Mila, their driver, who was awesome, from the airport and back.
Would definitely stay here again.