Michel's flat is perfect, and Michel was friendly and helpful, although he was not able to meet us personally. The apartment was just renovated and is beautiful, modern and very comfortable. The sofa bed is as comfortable as any regular double bed.
The location is fabulous. Terrific shopping along Boulevard Saint-Michel. Our favorite shops were Cote a Cote (reasonable fashion), Barlaim (leather jackets, Timberland shoes) and Sorbonne Cour (very nice leather bags). There is much more.
Notre Dame is a 3 min walk. The Louvre is within walking distance, across the romantic LOCK bridge. The Eillel Tower is a direct train, and the Arc de Triomphe is easy to get to as well.
We stayed 6 nights. Two nights there was a bit of noise down below. But if you go to sleep late as wake up late it's no problem.
If we ever return to Paris, we will definitely stay in this area, and will look for one of Michel's beautiful apartments. Perfect.