Our stay at Sixtine's place was rather good. The Apartment looks just like on the pictures and had enough space for the three of us. Furthermore we had everything we needed to prepare dinner at our disposal (from microvawe to toaster).
Whenever we had a question Sixtine would reply within an hour which was really great !!
The only real problem is the noise the small streets generate at night. It won't bother you at all if you keep the windows closed, but with the heat in Paris during our stay this became quite problematic.
Besides that Sixtine's apartment is a great place to stay for a Paris Trip due to its great location at the heart of Paris !!