I staid here in November. Very small boutique hotel in the first arrondissement, that's in an ideal location. The hotel maybe has 3-4 rooms per floor and do not expect an upgrade as it is a Design Hotel. I had two rooms and neither were upgraded as a Plat100. Also, no breakfast either.
The rooms were small by American standards but very nice and new which I enjoy. The Westin is a couple of blocks away which is nice too but a little older. I'm still deciding which one I like better.
The spa wasn't open when we were there and I could not find any mention of this on their website. The gym is the smallest hotel gym I've ever seen but the pool is nice with a small sauna type room.