Yankel's apartment was a great location--once you turn left out of the apartment, the first road on your left is Rue des Petits Carreaux--which turns into Rue Monorgueil. This is a GREAT location for popping into restaurants and coffee shops. Additionally, there were many close by transportation options. My one slight critique would be that, it would have been helpful to know that one of the stations closest (Strasbourg-Saint Denis) would not be accessible by line 4 during our stay. However, it was not too big of a hindrance.
The street that the apartment is located on is rather quiet, but that was a welcome respite after lots of sight-seeing. (And, as mentioned in other reviews, sight-seeing will not be the end of your workouts. Climbing up to the 5th floor [4th if you go by European floor numbering] toned my legs! But it felt safer being further away from the ground floor--so, a trade off.)