We are extremely pleased with our choice of apartment. It was clean, very spacious (which is exceptional for Paris for such a good price), very bright, and equipped with all essential amenities.
The host, Hélène, is a wonderful women. She was extremely helpful. She really surprised me when she installed wireless internet after I had already booked and payed for the apartment. (When I was booking, I did not notice that there was no internet there (which was clearly stated in the description). Only afterwards did I realize that and wrote to Hélène to inquire. In response, she promised to install internet, and so she did.)
Also, she was very flexible with check-in and check-out times, which was very important for us. We took taxi form the airport (which was a bad decision) and got into a very bad traffic, so were late by an hour or so for check-in; she waited for us without any problem.
The apartment is located very close to RER B Port Royal station and Denfert Rochereau station, which makes it very convenient for trips outside Paris as well as reaching both airports on public transport. And it is very close to Luxembourg Garden and Botanical Garden (which I appreciated a lot as I jogged in both). Even though the apartment is not located in a very touristic location, it is very convenient for reaching everything, unless you are reluctant to walk some 10 to 15 extra minutes. And it's just 5 minute's walk form Rue Mouffetard/Latin quarter, 5 to 10 minutes to Luxembourg, etc.
The view from the windows was one of the highlights - you have the Pantheon just in front of you, as well as a lot of greenery and sunlight.
To sum up, I definitely recommend this place and will myself try to come back if I happen to need an apartment to stay at in Paris.