I stayed at the apartment with my wife and teenage daughter. We loved it and would definitely stay again. The apartment was very clean, was fully equipped and is indeed in a great, central location. We expected a lot of stairs (and no lift) as Flavio makes clear in his information, we saw them as a fun challenge each day - but yes, they are exhausting. We slept well every night!
Although the apartment is small it is very well designed, my daughter particularly liked the loft bedroom, and there is enough storage. We stayed for 5 nights and it was comfortable for us and all our belongings. We'd recommend the 365 bakery along the street, lots of interesting shops and restaurants close by and the metro is only a few minutes walk away. Top tip: take a shopping list every time you leave the apartment - minimise trips up those stairs!