The apartment is really nice. Perfectly located, close to Charles Bridge, close to the Tram and the city center, close to nice restaurants... The park nearby is convenient for walks while being a bit steep.
On the small draw backs, be aware that the curtains are not opaque, meaning that you will have light pretty early in the morning. The apartment is located in front of a school, making it inconvenient to walk in light clothing in it... There are two blankets on the bed, one per person instead of a big wide one.
I highly recommend la Cantina nearby, an awesome Mexican restaurant with a really nice staff.
Daniel was amazing, we patiently waited for us in the afternoon, we were a bit late. He gave us great tips (upper part of the street is for tourist, lower part is for locals...) and without him we would not have had such a great trip.
Would definitely come back.