Christian's place is in a very nice spot for touring Paris. If you don't mind walking you can reach most of the attractions on foot as we did, or, otherwise, take the metro from the stop just 2 minutes from the house.
We were lucky enough to visit Paris during sunny days and the place (being at the fifth story, having big windows and wooden floor) looked really beautiful. And, although we were five adults (complete family!), there was enough space for everyone.
Christian is a nice and friendly man, always available when needed.
Thank you for being a great host,
Luca (and the family)