We stayed more than 2 weeks in this flat with our 4 kids aged 4-13 and I can say that the flat was cosy, perfectly clean and absolutely spacious for the all of us. Mohammed (we didn't meet Armelle) is the most kind and friendly host you may ever meet: he is fast in answering , very flexible in check in time, punctual and really attentive to his guests.
We were travelling with a van which didn't fit in his garage and he menaged to find us another parking place nearby for free, safe and covered; since we stayed for a long period he offered to send us a cleaning woman to his expenses which not only cleaned everything but even changed the beds (like in a hotel!); we have a 4 years son and Mohammed let him find special extra toys for him (he has 2 much older daughters).
Last but not least, he has in the flat a desk with several guides of Paris and Belleville, very useful for those travellers who want to go out from the mass tourism tracks.
He explained us everything about the flat and the quartier. Neighbourhood is very multi ethnical but also quite and safe, at night we slept really well, no traffic at all and no other kind of noise were disturbing. To get to the centre it is very easy since the metro stop is just around the corner (in less than 15 minutes you reach Hotel the Ville) together with supermarkets, organic shops, bakery, pharmacy, cafes and a useful print shop were you can easily print your reservations for the museums to skip the lane (several museums do not accept electronic tickets) .
The kitchen is rather basic but considering you are on holiday it is ok since you usually want to cook something fast and simple. The park, 3 minutes away by walk, is just marvellous, for kids and grown ups with its lake, cafes and play ground.
Shortly if you are looking for a place to stay in an area of Paris where true Parisians live and go to spend their free time go for this one!