I stayed in Karen's place for 4 nights while in Paris for work. This tiny studio is very well located and a good value for price, since this is a quite expensive area in Paris. It's right next to Parc Monceau (which I strongly recommend!) and just a 10-15 minute walk to Arc de Triomphe. The closest metro station is Courcelles, in line 2, really close and very convenient!
The only few downsides were that Karen was about half an hour late for our scheduled check-in, meaning I had to wait alone in the street with all my bags; and the fact that there was no toilet paper available. I do believe this might have been a one time thing, and other guests might not have experienced it. There was also no duvet, but there was a blanket and a bedspread available.
I recommend this place and would stay there again for its good value and super convenient location really close to the office.