We stayed here for a week and absolutely loved the space and location. The apartment is plenty big for two, or even four with the futon. There are black out shades in the room, so you can sleep really well. We used the washing machine a few times, so if you want to pack light, you will be able to have clean clothes. There is a steep flight of stairs to get to the unit, so we would recommend packing light (lesson learned).
The location of this apartment is fantastic. There is a Monoprix (Target) across the street, so if you need anything when you get there, it's very close. There is a metro station right outside of the door to the apartment, so you can get anywhere in Paris without walking a ton, if that's what you're looking for. We bought a 5-day metro pass for zones 1-3 which got us everywhere we needed to go. Versailles is outside of this zone, but you can just buy a one day pass if you're headed that way.
We found several great food spots within a few blocks of the apartment as well. Le Pain Quotidien was a great spot for breakfast, Nove 9 was fantastic Italian, and there is a Starbucks about a block and a half away.
The trip back to the airport took about 2 hours because of the RER train being down on two of four tracks. It was a bit of a nightmare, but I doubt that's the norm. The trip is supposed to take approximately one hour, just be advised that you should plan plenty of time to get to the airport and go through the process. The more time, the better. We left the apartment four hours before our flight was to take off and we checked our bags at the ticketing counter as our flight was starting to board. We made it on time, but it was very stressful. Plan plenty of time.
We will absolutely stay here again when we return to Paris!! We loved the space.