First, Nathalie is an excellent host, replying quickly to any request and always willing to help.
The apartment is in a good location, nearby a nice area for going out with lots of restaurants, bars and shops. It also easy to go to the city center.
We were staying 2 months in the apartment as we were moving to Brussels. Therefore the following comments should be read from the perspective of a long-term tenant.
The apartment is very bright, spacious and offers nice views over the roofs of Ixelles. Our main issue with the apartment is the severe lack of soundproofing: the house is old, of average build quality and soundproofing never seems to have been addressed. One can hear the neighbors talking even if they talk at normal levels. And if someone walks above you, the walls start to shake and you hear every single step. The apartment is on the 2nd floor, sandwiched in between two neighbors below and above. The noise level from below can be tolerable, however, the noise from above is unbearable, in particular when the neighbor's children are staying (every other week for one week). Then it is like a herd of elephants is trampling over your head all day long.
For short-term travelers this certainly doe not need to be an issue and therefore I would highly recommend the apartment for a group of travelers who want to explore the city and use the apartment as their base mainly for sleeping.