The photos do not do this apartment justice. It's very stylish and comfortable, with plenty of room for our family of 3.
The apartment is in a great location: it's a very easy walking distance to metro line 4, RER B and multiple buses. Despite being on a major road, the apartment opens onto an interior courtyard, so it was quiet, and cool even during the dreaded canicule.
It's about a 20-minute walk - and a beautiful one - to the Orsay or the Louvre, about 25-minute walk to the Pompidou, and just about 5 minutes to the Sein. You can easily take the RER B direct to the catacombs and I forget which bus takes you to Montparnasse, but it picks up right around the corner. A perfect spot!
Check in was pleasant and easy, and the company provides a lot of information for your stay. We'll definitely keep this place in mind for future trips!