We certainly enjoyed our stay. The balcony/patio was a wonderful place for views and sitting at the beginning/end of the day. The 20th is a bit remote from the big attractions (e.g. Louvre, etc.), but only a 20-minute walk+metro trip most of them. And for us, being out of the tourist district is a BIG plus. The cafes are for locals and priced accordingly. Another big plus is that the building location is quiet (for Paris, not Resume-Speed, Nebraska) as it is not located on a main street and has a courtyard and another building between it and the first big street. The tourist district can take a lot of energy out of you, so it's wonderful to have a beer (purchased at a nearby Carrefour/Franprix) after soaking up culture.
The unit is also big enough that you don't feel cramped. We've stayed in places where whatever you wanted was behind something else (often breakable) and two in a room led to countless pas-de-deux - the petite chambre is tres petite.
Aristid and Patrice were quick to respond to the questions we had and helped us when our AT&T phones refused to work while in France - we had no problems with Verizon.
In summary, we would heartily recommend staying here.