My wife and I absolutely loved our stay here and we would stay here again without a doubt.
To keep your expectations realistic, I would point out the "worst" things which may be deal-breakers for some people:
the walk up is about four flights
the bathroom is separate, small, and a short flight of stairs down from the room
the low, slanted ceilings will have you bumping your head on occasion
These things did not bother my wife and I at all but we can see how this may not work for some.
The positives are so many though! The main one being Nicolas himself who was wonderful in all respects. He was a fantastic host and we felt secure knowing that if we had any issues, they would be taken care of. His advice and knowledge of the area was also invaluable and spot on.
There is also location, location, location. The view out the windows was better than pictures show, actually. My wife and I made pasta the first night while staring at the Eiffel Tower. We will never forget that! Then there is the proximity to all of best Paris can offer.
The amenities were many and we needed very little as so much was already included.
Highly, highly recommend!