I stayed with my boyfriend at Lo's appartement for 8 nights in June. For us, it was a great spot near the places we had to go (we were there for a poetry competition in the 20th district). It was calm, not really noisy. It's small, but everything is there, including a kitchen with facilities : for breakfast it was great, thanks to her son who left fresh bread for us. However, it was quite humid, maybe due to the weather in June, so bring summer blankets instead of sleeping bags! Also beware of the stairs, we haven't found the light the first nights.
I must say I haven't met Lo, unfortunatly because she was out of France, but she seems to care about her guests and wants to welcome people as friends of friends. So if you don't like hotels and want to feel like people living in Paris, it's a good choice, in a great neighborhood, calm and not far from subway stations.
And go take a look to the Parc des Buttes de Chaumont, really close with a lot of trees and trails!