In a nutshell, this unit is nothing short of fantastic. I'd stay here again in a heartbeat on our next trip to Paris.
Some details...
Location - I can't imagine a better location. Just steps from the Seine and less than 2 minute walks to both the St Michel and Cluny-Sorbonne Metro stops. The unit itself has views of both Notre Dame (amazing from the balcony) and even the Eiffel Tower from the main bathroom. It's also just steps away from literally hundreds of restaurants.
Unit itself - the apartment itself is exactly as advertised. Actually was bigger than I expected. There's a full kitchen if you want to cook (we made eggs for breakfast a few times and warmed up some leftovers). The washer/dryer is also great for those long stays. Bed was comfortable and the unit has heat/AC for temp control.
Michel was fantastic. From the time we make the reservation until we checked out he was extremely responsive. He provided a great list of restaurant recommendations that we took him up on - all great.
As mentioned in most of the other reviews, there are stairs to consider as the unit is on the third floor and there's a spiral staircase to get to the bedroom. It wasn't an issue at all for us, but needs to be considered for those with mobility issues.
All in all - just a perfect place to stay in Paris. I'd stay again in a heartbeat.