Great one bedroom flat on the top floor. Note that this may not be a great place for a tall person since the ceilings are low! Mostly you'll notice this in the shower (you can sit and bathe though). My son is 5'7" and had no issues.
Tiny but new elevator (just big enough for one person and a bag or 2 people and no bags) takes you all but the last flight up. The apartment is small but very comfortable for 2-3 people.
Bed is great and the kitchen is big enough for simple cooking with 2 burners and plenty of dishes and silverware as well as a few pots and pans. Nespresso coffeemaker worked perfectly. The couch was fine for sleeping as well. Nice big TV with fast internet and a great select of popular and recent movies was a treat.
We loved that the windows all open for great air circulation and a view of Paris roofs. Since it was April we didn't use the heat.
Washing machine was convenient and clothes dried quickly on racks stored above the door to the apartment. The place was super clean.
The neighborhood is really the best for touring Paris since it's so close to the Louvre, Notre Dame, and the metro (2 stops within a block or two). There are so many great restaurants within walking distance and lots of fun shops on rue Saint Germain. St. Sulpice is just a block away and you can see its towers from the window. There's a grocery store a few blocks up the street.
All in all a great stay and a great way to show my son my favorite city! He loved the place too. Definitely recommend!