Great value! As per the name, these are more like small apartments than hotel rooms, with a small kitchenette, dining room, desk, and bed in a studio layout.
Location is excellent -- it's on the Velodrome exit of the tram, and well situated. I was visiting INRIA, which was a short, pleasant walk. There is a supermarket nearby and two restaurants downstairs, and the aforementioned tram is an easy way to get to downtown Nancy and/or the train station.
It was comfortable and clean. Not 5 star luxury, but then you would have to pay many times the 50 Euros a night to get that type of luxury. For conference and longer term stays (> 1week), it was an excellent facility in an excellent location.