This is a perfect stay.
The studio flat is very clean and has everything you could need. Nice shower, and kitchen facilities and really quite spacious for a studio too with high ceilings.
The building is stunning. The hallways are lovely, the neighbours are very friendly (with lots of cute pets) and the receptionist goes out of his way to help.
The area is my favourite in Paris. The location is within walking distance from everywhere. It's great because in 15 minutes you can go to the Louvre area which is full of recognisable brands and cafes and in the other direction you can get towards Sacre-Coeur with its more authentic and rustic patisseries.
The only possible drawback is that the sofa bed is not the most comfortable but you get used to it after a few nights!