The appartment is clean and nice, with a stove, fridge, microwave and espresso machine. The apartment has heating, so winter days were warm for us. Hosted 6 people (3 kids) on 4 beds. To get to the apartment you have to pass through a locked courtyard door, and then a locked building door, so the security of your belongings isn't an issue.
The location is superb it is in a walking distance from a lot of tourist attractions and is 3 mins from Metro/Subway.
Alberto (the host) was very responsive and super helpful, providing with all kind of information before our arrival and through out our stay.
Overall we had a great experience and I would definitely recommend the place to a groups of 3 to 6 people who's willing to explore the beauties of Paris.