We thoroughly enjoyed Jan and Sarah's place. We didn't meet Sarah, but Jan was a wonderful host who was super responsive to questions, helpful, understanding (when our text messages failed to go through), and flexible with respect to check-in/check-out. We left our car in their secured parking area, and Jan drove us and our luggage to the apartment (which is about a 10 min walk away).
The apartment is just around the corner from Old Town Square and down the street from Tyn Church, so very centrally located. We enjoyed being able to pop over to the apartment to take a break from sight seeing, sit and relax, use the bathroom (for free!), and grab a snack. The apartment is located in a very lively area, with lots of young people in bars and restaurants, particularly at night. However, the apartment (the former stable of a grand building) is super quiet, which was great for sleeping. There is no AC, but Jan provided a fan. (The apartment has plenty of natural light, but it is located on the ground floor and didn't get any direct sunlight, so we didn't actually need the fan.)
The king size bed was a treat (so rare in Europe), and the bedroom is large, which allowed ample space for luggage without tripping over it. The kitchen was functional, and we appreciated the coffee pods and cocoa powder to be able to make ourselves cafe mochas in the morning. There are supermarkets (open until 10 pm) about 7-10 min walk away; there one could get anything else one needed at great prices.
Extra thanks go to Jan, who allowed us to leave our car a little longer (so we could see more of Prague) and was super accommodating to our schedule. He is happy to share his thoughts on the city and the people--not just his planning guides, but anything you ask (and his English is great). We look forward to doing the same for him when he comes to California next year.