Overall, the Dining Room is a great way to get really upscale food for a great price (about $35/person for three courses without drinks). I let the staff know I was vegan ahead of time, and the chefs were able to come up with a nice menu, a beet salad w/ artichokes, some sort of risotto, and a bean cassoulet. The only thing I was sort of shaky about was the service - we got the amuse bouche twice, and for a little while it was unclear who the server actually was. I would definitely go back for lunch or another dinner though.
I actually visited again recently, and I was very pleased. The chef again took very good care of me, a very tasty salad mixed green w/ fried tomatoes, seared tofu, and a dessert trio of sorbets. The service was quite good this time around.