I stayed for 2 months at Britney's apartment and I can really recommend it, especially for a long-term stay.
The apartment has everything you need. It has a large and well-equipped kitchen to cook meals, a great bathroom and a washing machine which is especially convenient for a long-term stay.
The check-in and check-out were very easy as well and Britney provides you with all the information you need. In general, Britney is super helpful and very responsive if you have any issues.
Last but not least, the location of the apartment is great. You are super close to Gare de l'Est which hosts 3 metro lines and allows to get anywhere in Paris very easily. You are also super close to the Canal Saint-Martin which is a super cool area with many restaurants, bars and places to hang out.
Overall, I can really recommend Britney's apartment.