The apartment is in a great location which is very quiet at night but also right by the main train station and a tram stop. It's also only a short walk to the Powder Gate and Wenceslas Square.
There is plenty of space for a group (we had 3 adults and 2 children) although the stairs up to the mezzanine level are steep so not suitable for small kids.
The kitchen and bathroom are great although we found the apartment a bit cold (the heating in the whole building was not on for the winter yet).
Overall we would recommend this apartment for a stay in Prague.