We stayed 6 nights in July 2016 (during the Euro Cup!).

Pros: Description is very accurate. Apartment is great. It seems like Thierry has thought of everything - kitchen & bathroom amenities, guidebooks, maps, international calling, internet... and more. Just right for 2, fine for 4 CLOSE friends.
Apartment could not be more central. You are IN THE HEART OF PARIS. Perfect location, especially for your first visit. The first night, I strolled out to the bridge over the Seine to see the lights on the river. A young couple was kissing and a street performer was singing "What a Wonderful World."
Shops, eateries, bakeries on the street below. A convenience store is 1 block away and 2 "supermarkets" (city-size) are a 10 minute walk.
Close to 3 useful Metro stops (use N.D.- St. Michel for RER to Versailles and CDG).
The photos don't do justice to the large amount of balcony space (lengthwise) it has.
If you are concerned about the lack of air conditioning, don't be. We had a heat wave (31 deg C / 88 F), but you just open the FIVE windows and the breeze flows through. We were never uncomfortable.

Super-Pro: NOTRE DAME!!! Our favorite. You can see it from the window. We will miss the bells most of all. A sparrow living in the trees between the cathedral and the bridge landed on my finger and ate bread from my hand.

Advice: Like any "all-in-one" washer/dryer, you have to plan ahead. We did and it worked fine.
We found Carrefour supermarket to have better selection (for an American) than Franprix (they are next to each other).
Good vegetarian restaurant: Cross the "Notre Dame bridge," go a block, down street to left.

Cons: Uh...honestly none. Just read the description so you are not surprised by anything, like climbing stairs.