I stayed in the apartment for 5 days with my boyfriend, everything was absolutely perfect, the owners have been very kind, precise and fast in answering to all of my questions. The apartment is perfect for two, big enough, warm and perfectly clean, I fell in love with the furnishing, it's beautiful and very comfortable.
As for the distance from the city center, you need about 15/20 minutes by walk, but if you prefer there are metro and buses to go everywere, and they are very close to the apartament.
I would totally recommend it, I have tried lots of houses on Airbnb, and this has absolutely been my favorite one!