This is a very quirky place to stay. I think it would be great for kids, with its outdoor terrace and kid's room. It is very homey and lived in. One is asked to water the plants and feed the turtle--that's the vibe.
As a business place to stay I can't recommend it. The entryway downstairs is dark, dirty, and smelly -- I wouldn't feel comfortable inviting colleagues over for a drink.
Although it has air conditioning, if you are there during a heat wave, as I was, the bedroom loft area is stifling. The apartment is crowded, with shelves overflowing, and a small tight kitchen. If there were half as much stuff in this apartment it would be twice as nice. (Things like dried rose decorations collect dust and don't add to the atmosphere.)
Sephora and her partner were very helpful, and allowed me to leave a suitcase there before my stay. The metro is right around the corner, but the 11th is a little out of the way for many of the major sites of Paris.