This is a great option for a short stay in Prague. I stayed by myself, but the apartment will easily accommodate four or five people. Klára and her son Jacob were friendly, timely, and accurate with all communication. My flight got delayed a couple of hours and Jacob was kind enough to wait for me. After receiving the keys and saying good-bye to Jacob I had a bit of trouble opening one of the doors (by my own fault, I forgot to try one key), and Jacob was kind enough to come all the way back to help me.
The apartment is well located. If you want to go to city center, it's a 15 or 20-minute walk, but tram and metro stations are nearby. I would definitely stay there again.