In general, the Mercure is fine for a short business stay but tends to be on the high price side since there are not many options in Les Ulis. I stay there several times per year. The restaurant is nice and the people are friendly. The main issue with the Les Ulis Mercure (common to IBIS, Mercure and Novatels I have stayed in) is with the temperature of the room. Although there is a thermostat, there is, in principle, no air conditioning,(if so, I have never seen it work in 5 years of going there). You can open the window but the heavy curtains block the air flow. If you open the curtains, you suffer from bright lights on the outside of the building and significant noise. (It is close to the expressway and airport.) If you need a cool room to sleep, you may have a problem at the Mercure.