We stayed in Eric's apartment for a month and enjoyed it very much. We liked the eclectic furnishings and beautiful drawings, but especially we loved all the books. There are collections of Asterix and Tin Tin and other comic books and also English novels in French, Proust, picture books on art and archaeology - and many more.
Temperatures in Paris were around 28-33 deg most days, yet the flat stayed cool. The main room looks out onto the busy street (with a view of Sacre Coeur); the bedroom faces the courtyard and is very peaceful. Transport is easy, with all the metro lines and the bus station at the Gare du Nord, plus the lines from La Chapelle almost opposite the flat. You can also walk into town - the Rue de Rivoli took about 40 minutes. NB to reach the apartment from the Gare du Nord, look for the Gare Routière BUS signs and you will come out halfway up the Rue de Faubourg St Denis, from where the apartment is a short walk.
The area has a large N African/Indian/Sri Lankan population and the shops reflect that, as does the best Parisian market we've been to - the Marché Barbès, on Saturdays and Wednesdays. The fruit, vegetables, herbs, meat and fish were great there and, unlike in a lot of markets, they were considerably cheaper than in the supermarkets. There are local grocery shops nearby but also a range of supermarkets like Lidl, Leader Price, Franprix, G 20, Carrefour - nothing is far. There are so many boulangeries and patisseries we didn't get to them all.
We would happily stay here again.