The location is very good. Even if Belleville is not the hippest neighborhood in Paris, the apartment is near two metro stations. Besides that, Place de la République and the Marais further south are within reasonable walking distance.
The message exchange with Stella ran smoothly and she promptly arranged the fans we needed to endure the sweltering Parisian summer.
The apartment is rather big and well equipped. I just missed a coffee machine and a suitable pan to make scrambled eggs for breakfast.
The double bed and even the sofa bed in the living room are very comfortable. The linen and the towels were clean.
The apartment had one flaw, though. In front of the building there is a very busy boucherie that loads lots and lots of vans with halal meat from early morning. The loading metal carts are extremely noisy and woke up everyone in the house almost every day.
If you plan to wake up early to enjoy Paris, it won't be a big deal.