Check-in: You have to take the key of the apartment in the office of Ruterra, which is located in front of the Main railway station of Prague. The guys who welcomed us have been nice and helpful. Then the apartment is 15min by walk.
Location: it's 3minutes by walk from the Town Hall of Prague, and 5minutes by walk from Square Venceslau. So the location was perfect!
The apartment: the apartment is very hot (perfect during winter), beds are comfortable, the kitchen is very equipped, and the shower is beautiful. The only negative thing was that the handrail of the mezzanine was not stable, and in my opinion it was quite dangerous. And an other thing was that for beds there was only 1 duvet and 1 pillow case per persone: no blankets and no sheets. I didn't appreciate this so much.
In the end the apartment was good, and I recommend it to everyone who want to stay in the centre of the city for a very good price.