The studio is a good size, especially for Paris. I was there alone, but the bed would be big enough for two, plus there is a pull-out couch. The flat was clean and well equipped as expected (bed linen, bathroom and kitchen). The windows at the front open directly to the street, so it can be a bit noisy, especially with the windows open. I was there in the winter, so I had no problem with this. A bit of noise also comes in from the main entrance of the building, since the flat is located right next to it.
The location couldn't be better! The M13 metro has a stop literally one minute away (Pernety), the M4 is about 10 min on foot (Alesia). The M13 takes one directly to Champs-Elysee, whereas the M4 is one of main lines in Paris, with direct and fast access to Odeon, Notre-Dame, Les Halles, and the two main train stations (Est and Nord; this is priceless when arriving and/or leaving by train).
For food: there is a Carrefour two minutes away, open till 10 p.m., and a MonoPrix about 5 min away, also open late. Or, one can have takeout from many small places within a two minute walk (pizza, Chinese, kebab, various bakeries, etc.).
Overall, I had a great time! The host, Marie, was immediately available when I had to set things up with her. We didn't need to communicate much, because everything was set up nicely, plus I already knew Paris very well.