Have to agree with dizfan - on our trip before last, DBF loved LeCellier and that was his only request when planning our last trip earlier this year. I made the ADRs for LeCellier (dinner) and also for Chefs de France (dinner).
DBF was disappointed that LeCellier wasn't as good as he remembered it (I thought it was good, but not great like last time, too). On our last night, we had dinner at Chefs de France and could not belive how good it was. I asked him if he thought it was good because he had low expectations or because it was truly good food and he replied the food was truly good, better than the French restaurant we go to at home.
You guessed it - for our next trip (fall 07), his only request is dinner at Chefs de France...
As for specific reasons why...we both thought the food preparation and presentation at LeCellier has slipped. The food seemed to be "thrown" on the plate instead of placed and it was sloppier (drips on the side of the plate, etc). Also, because of the "it place" status LeCellier now has, it's more crowded and the attention from the servers was less than before and our courses all overlapped.
We knew that Chefs de France would be crowded and "cozy" in keeping with French bistro tradition, so that didn't bother us. Had we not known, however, it could've been a different story for DBF (likes his space). The food was excellent, the bread was warm and fresh, the servers were extremely attentive and knowledgable, and we weren't rushed.