We had a great stay at the apartment.
The location is perfect right in the city center (we walked everywhere and didn't have to take the metro). You are really close to Charlesbridge, Prague Castle etc..
The apartment is very clean and provides everything you need.
Karolina is very nice she gives you every information about money excahnge, restaurants, bars and anything else you might need.
With the window open it can be a bit loud since you are in the citycenter, so I wouldn't recommend for families with small kids. But if you like being close to all the bars and restaurants this appartment is perfect.
We found nothing to complain about.