I spent 4 and a half months in the apartment while I was in Paris as an exchange student at l'Université Paris 1 Panthéon-Sorbonne.
First of all, the apartment is well situated in the 8ième arrondissement which is a very safe and quite wealthy neighborhood. The métro connections are very good, the big train station "St. Lazare" where many métro and bus lines are accessible is about a 10-minute walk away. During my stay there was one of the biggest social movements of all time in France, which highly disturbed all public transports, but the great situation of the apartment made that situation a lot easier to handle.
There are multiple supermarkets, pharmacies, restaurants and places to get cheaper snacks very close to the apartment. There is also a launderette where I did my laundry. The "Grands Boulevards" with their big and famous stores "Printemps" ou "Galeries Lafayette" are easily reachable by foot.
Still, the situation was not perfect for me, since my university is situated in the south of Paris, so it was quite a long ride every morning. This is the case for most of the educational institutions in Paris, so as a student I would maybe suggest to look for something that is on the left side of the Seine or at least closer to the center of the city.
When it comes to the apartment itself:
The living room downstairs looks okay and is clean, but the only chair in the apartment is very uncomfortable, so it is not suitable to sit on it for longer periods of time without experiencing back pain. Therefore one cannot really spend a lot of time in the apartment besides from laying on the bed.
The kitchen unit is suitable for very easy dishes, although it is quite uncomfortable to cook there, because the cupboards are placed above the ceramic hobs, so it is difficult to reach them while standing straight up (I usually cooked while sitting on the chair).
There is a cupboard in the apartment which is practical to store shirts and jackets since it has a clothes rail. There is also enough space for a vacuum cleaner and other stuff needed for the household. Generally speaking, the apartment offers quite a bit of storage despite its small size.
There is no real shower, just a bath tub without a shower curtain. The ceiling on the upper floor is very low, so you have to crouch all the time, especially as a tall person.
The windows are right over the bed and are basically not insulated at all (now a little bit, because I tried insulating them myself), so it gets very cold during the winter, because there is constantly cold air coming in. Douglas did offer me a small radiator though, which I could use every night to combat the cold air from above.
The stairwell looks very old and dirty and it is a real pain to go up 5 floors every day without a lift, especially since you will have to do that multiple times a day to buy food, do the laundry, etc.
After my first month, the water tank started leaking right next to my bed and had to be replaced, so this problem should be solved now. After that the sink started leaking as well and still is as I am writing this, because Douglas did not find it necessary to repair it, after I told him. After a while I got used to the constant sound of dripping water, but sometimes it went onto the floor, when I did not pay attention.
Douglas is a nice and very helpful host. His English is excellent and he is very responsive when you call or text him. He will (most of the time) do what he can to make the stay enjoyable. He is open for all sorts of questions and will always advise you when you ask for it, that is a big positive.
All in all, the apartment is overpriced in my opinion, even though the host is indeed a super host.