This duplex is pretty great. The building is well located, has an elevator and it's very near a tram station, making Prague 1 easily accessible within minutes.
The apartment itself was as announced. The upsides are: It has a good size, the 3 foldable beds are big and somewhat comfortable, heating is good, the upstairs bedroom is very spacious, the kitchen is well equipped, wifi was good and it has a washing machine. The only downsides are the shower (which is too low, making me have to shower sitting down) and that downstairs has no curtains, making whoever is sleeping there wake up to sunrise. That's it. Would definitely come again and recommend to friends.