This is a great place to stay in Prague. It's close to the bus terminal and bus stop from the airport and also walking distance to the old town. Personally I think it's better to stay a bit outside of the old town so that you are not affected by noise!
The apartment itself is clean, bright and rooms are lovely. I slept very well. As with many airbnbs I wish the check in was slightly earlier. You can store your bags in their office but when you arrive to a city you want to freshen up etc so even 1 hour earlier check in would be great. Overall though no issues and would highly reccommend this place.