Everything at Casper's apartment was great. The bed was cozy, shower was nice, and the kitchen was better than what I've got at home.
The location isn't in the heart of touristy Paris, but where it is, near the Canal St Martin, is so lovely in a way that most visitors would miss. It's a real slice of life in Paris, with great cafes and bars. (Radiodays, a nearby coffee shop, was my favorite place to relax in the city.) there are plenty of trains that make it super easy to get anywhere you'd like, though.
And also, don't let its location near the hospital go unnoticed: my boyfriend unfortunately suffered from a kidney stone the last night we were in Paris, and the emergency unit was a 10 minute walk away. For visitors to a foreign city, it was extremely comforting, and it's certainly not a thing we'd thought we would need to take advantage of.
Couldn't recommend it more; it felt like a home away from home by the time we left.