I had very high expectations for this place when I initially booked it, but I was unfortunately disappointed by my actual experience. We were only here for one night, so it didn't really have a chance to get better. Starting with the pros, it is very well-located with plenty of options for restaurants, shopping, and transportation. Also super close to the catacombs, which we did not get a chance to see.
The check-in process was the worst of it. At first, it wasn't clear that we needed to "start check in" in the app to see the steps for self check-in. Then, as we were following the directions, one of the keys wasn't working, and we had to have Nicolas come and help us - not a true self check-in. This all happened at 11pm, and I did not have an international phone plan, so I had to use the wifi at a nearby restaurant to send him messages as we encountered issues. Fortunately, he came rather quickly, but he was not very warm or sympathetic (given the circumstances) when we met. The apartment is on the 3rd/4th floor, but there is no lift, so be ready to carry your things up. When we finally got in, the wifi password was so long that we entered it wrong multiple times - I eventually had to write it out on paper so that I could read it as I entered it. Then, the balcony. The balcony is not in fact a balcony as it is too small for an adult person to safely stand on. That was one of the things I was most excited about when I booked (along with the self check-in), so I was very disappointed. We were given towels but no shower soap, and there was no toilet paper in the bathroom upon arrival (we retrieved it from a different space). We were excited to use the washer/dryer, but it was already in use by the adjoining apartment (I wasn't aware it would be shared), so we could not use it. Finally, someone tried to come in to the room (I guess to start cleaning) prior to check-out while I was still in it, which I thought was unprofessional.
Overall, the apartment is well located and generally meets one's needs, but we did not have a great stay, due to a combination of unmet expectations (based on the advertisement) and our specific circumstances.