I tried the restaurant, for breakfast and dinner, and I agree with you. There's far better in Paris when it comes to michelin starred restaurants, and not only within the 3 star category (l'Arpège, Astrance, and even La Tour d'Argent, who was downgraded, go higher in my book). I still need to try l'Epicure who has received rave reviews.
However, for a hotel restaurant, the quality is still phenomenal, especially when you compare it to other 5 star hotels in major cities.