When we booked Edward's apartment we were worried because there were not many reviews as it is a newer unit, but it was much nicer than we expected. The location is incredible (above one of the best tourist squares in the city), and it has views of at least five different classical structures from the deck. From the apartment you can hear the bustle of the street below, which is interesting and exciting (especially for children) but isn't too loud if you keep the windows closed. The only downsides are that the furnishing is very generic Ikea furniture, although it is very nice (especially the beds are very comfortable) but not unique or interesting. There is a giant clock window which is very unique and interesting, as is the rooftop deck.
Check in is great with a lockbox for the key and a code for the door, but the elevator up is very small so you will probably have to make multiple trips with your luggage. We had to leave our double stroller downstairs for the duration of the trip, but who has a double stroller in Europe? Also one bedroom is a loft without a door, which tends to get warmer in the summer. Not a big issue since you can open the windows and get a good breeze, but we were unlucky to be there during a mosquito spell and had some mosquitoes during our stay.
Overall if you are coming to Europe for interesting experiences you should stay here, it is an experience of its own.