Absolutely lovely apartment in a perfect location! You are right in Old Town Square and have a perfect view of the Church of Our Lady before Týn from the apartment front windows. You're centrally located, so you can walk to all the major sites in Prague from this apartment. If you stay during the Christmas and New Year holidays, you have a front row seat to the largest Christmas market in Prague and Old Town's New Year's Eve festivities!
The only downside to this places are the thin walls. It was especially bad on New Year's Eve as the fireworks in the area carried on until morning, then the street blowers started. You can hear everything that goes on in the stairwell and we were unfortunate enough to share the building with some loud tourists who liked to stay out late and have loud conversations on the stairs. You can also hear the restaurant and shop employees next to and below the apartment as they prep the start and end of their day.
Don't let the downside discourage you from renting this place! The pros greatly outweigh the cons! Just anticipate the thin walls and pack a set of earplugs :)