I stayed in Julia's apartment for three weeks as I was a student participating in a summer program through a university in the 7th. The best part of Julia's apartment is probably the location. It's conveniently located on the edge of the 8th and Av. Montaigne and Av. des Champs Elysees are a five minute walk away (both have tons of great shopping the former definitely more luxury). The air conditioning is definitely amazing as well, especially in July when it is blistering hot.
The apartment itself is definitely smaller than you would expect. I lived alone, and even then, it was quite a cramped space. I understand that many apartments in Paris are smaller, so this wasn't a downside.
Last, the WiFi connection is not great and during my stay it stopped working completely the last week I was in Paris. Julia was not really amenable about fixing the WiFi issue, so if you are a student or need a good WiFi connection for any reason, I don't really recommend.
Anyways, staying at Julia's was memorable to say the least, but honestly I'm not sure if I would stay here again.