We stayed at Vincent's place for 3 days. The apartment situates on the 6th floor, under the building's roof, and has no elevator to lift up. It wasn't a problem for us, and it pays off when you finally 'climb' inside the apartment. :)
We really enjoyed the cleanliness, big windows (a lot of light is over there!) and comfy beds. Vincent left coffee and water for us, described all the house's rules and gave us the key.
The location is great: several metro stations to Montmartre and 10-15 mins in another way, if you're going to the Cite direction.
If I could come back to Paris, I would definitely send the request to Vincent again!