I stayed with two others on a four week trip. Overall it was made okay by ease of public transport, but has the potential to be amazing. For now, it should be stayed at short-term with the idea that this solely for location. It is to be noted that this apartment is not really disability friendly: the elevator is just large enough for one person to stand, no wheelchairs.
PROS: It's the absolute perfect location for Metro and bus. The top floor view is awesome, particularly at sunset with the Hôtel National des Invalides golden dome lit at night. So pretty. It is shockingly quiet at night for such a busy street, too. The apartment was much larger than anticipated and the bedroom was not nearly as tiny as the picture makes it- massive bonuses. The host was quite nice, and I really enjoyed that he did not harass us or check in, and was responsive the two times I contacted him during the stay: one time to ask about a broom, the other to let him know I was checking out.
CONS: ****Disclaimer: I did not bother the host with these issues because they were either not fixable during our stay, or some things shouldn't need to be asked for**** Unfortunately, the two most important things for long-term stay were the cons: the kitchen and the washer/dryer unit. Every single utensil, plate, pot, pan, and glassware was filthy; some even still had food in them. The pots and pans were unsafe to use except one (broken handles, etc), the knives were so dull they wouldn't cut fruit, and the stovetop was cracked and questionably safe. The hinge to the kitchen window was broken, so the heat from the washer/dryer and cooking was unbearable (fridge/freezer worked fine, dishwasher never used). I bought a chef knife and some other kitchen wares because I ended up just eating a lot of salads and protein bars. I left what I bought for the next guests. The washer/dryer combination unit took an entire day to clean a few garments, so it was often much faster to handwash in the sink and hang dry than to use it at all. Bring your own clothes line. There are no drapes/blinds on the bedroom French door window, so I used an extra bedsheet fashioned into a curtain for privacy by wedging between the doors and frame. I'm pretty easygoing with beds, but the mattresses was very thin and uncomfortable, so the extra pillows available did help a lot. The shower is painfully small- you have to shimmy very carefully to open/close the door to not get water everywhere, and shaving my legs was difficult. That's not their fault per se, but it's worth mentioning if you are a larger person or have a disability.