Just completed a 2-night stay here. Pretty nice overall, although not without weird quirks.
The building is exciting to explore, an old monastery with lots of interesting features like an old chapel, library, some exhibits. Our upgrade was to a Privilege room in a modern annex (above the spa). Not sure if this is where they put the Americans on a hot day (our room had AC!), but in hindsight, we would have preferred a historic room. (It's very hard to tell from the website where rooms are located or what exactly you'll be getting ... looking at the pictures on the website, our room looked no different than a standard room). The room felt a little depressing ... devoid of nice touches and with a view of an ugly building a few feet away. If we were to return, I would apply SNA here and pick one of the suites in the historic building.
The numbering of rooms is very strange. We were in room 3xx, which was on the "first floor" and on the spa building elevator one has to press 2 (there's no 1). On our initial trip to the room, we wandered around for a while with our luggage and had to ask for directions twice.
Breakfast is available in lieu of points. It's one of the weaker buffets we experienced on this trip (scrambled eggs, bacon, sausages, beans, etc available, but not particularly tasty, and they're very slow to replenish). Ample choices of breads/pastries, but weak in the area of cold cuts/salmon/fruits. Strangely, the mediocre buffet is complemented by free-flowing Laurent-Perrier champagne, a very uncommon sight and pleasant surprise.
The website bills the hotel as "best in Northern France." Not per our experience with service -- they failed to provide housekeeping and when we returned at 7pm, the housekeeper had gone home and all we could do was get some fresh towels. An adjacent room had a room-service tray outside the door all day until our checkout at noon the next day. The front desk people weren't particularly helpful or friendly. Checkout took forever. Also, this was the only hotel of the 8 we visited in France/Belgium on this trip with no welcome gift. Hotel doesn't have online checkin and chat with FD features enabled.
The location is decent -- less than 10 minute walk to the center of the historic town. Not a lot of restaurants or stores in the immediate vicinity, and some really terrible postwar architecture around. But Lille is well worth a visit, and the hotel is a good enough base.