I've been both aware and curious about it for many years, so when I visited Paris in April, I made a point to track it down and take a few photos to use for this blog. It's a bit off the beaten track, about a 5-10 minute walk through a nondescript apartment neighborhood from the nearest subway stop. It's also 90 years old, but in pretty good shape, as the photos indicate. When I took the photos I didn't have reference material handy, so they don't quite match the viewpoints of photos taken when the development was new.
A much more detailed treatment of the rue is here. Besides period images, it has recent photos of the exteriors as well as some interior views.
That's a Voisin automobile -- very modern in those days.
I happened to take this photo from a similar spot.
Before the formal opening. The building on the left is Mallet-Steven's.
Workshop and residence of brothers who were sculptors.