We thoroughly enjoyed our 1-week stay at Carlos' apartment. The place is small but cozy (perfect for a single person or a couple), the bed is comfy and big, and the amenities work as advertised.
The place is located in a vibrant area with lots of bars, cafes, and restaurants that make it easy to have a fun time just around the corner. Supermarkets and metro stations are also both in walking distance of the apartment, which is great.
All in all: If you are looking to spend 7-10 days in Paris – either alone or with a partner – this place is definitely a good choice.
A small warning to anyone who happens to end up in the same situation as us: The apartment door has no handle (I don't know if this is a French thing or unique to this place). Instead, you have to both unlock *and* open the door using the key itself. On multiple occasions, we experienced that we could unlock the door but not open it, and we somehow managed to 'twist' the key inside the lock when trying. If this happens to you, *don't* force it! Simply lock the door again, unlock, and you should be able to open it. We ended up having to pay €70 for a new key, so it's worth keeping in mind.