The apartment is wonderful. A great location to be in: the main street that is perpendicular to rue de Greneta is very lively and full of restaurants, grocery stores, patisserie shops, and pharmacies. The apartment is nicely furnished, clean, and has a fully equipped kitchen and bathroom as well as all the linens for the beds.
The staircase is very narrow and quite lengthy therefore it took some getting used to and is not easy to carry luggage up on but it was a minor thing compared to the apartment. It is convenient that the key is in a lockbox so that if you're group separates, you can leave the key there and come back at separate times.
We would definitely come back again. We had 4 people in our group and fit comfortably. The pullout couch is not the most comfortable but after a long day it didn't matter that much.