We love Le Cellier.
We vacation on the deluxe dining plan every trip and we utilize it's value by doing a signature every night, including Le Cellier.
Is Le Cellier the best signature? No.
Is it romantic? No.
Is it quiet? No.
Does it feel upscale? No.
You have to know what you're getting as a whole experience when you go to Le Cellier, because many people go with the expectation of an upscale dining experience due to it's signature labeling and pricing. Being inside Epcot, it gets A LOT of families with young children and 99% park attire. The seating is close and it's a loud restaurant, but our service has never once been unpleasant and our food has always been excellent. We go expecting and enjoying the park feel, while still getting a very good meal. If you're going with the mindset of an upscale dining experience, then you're likely going to hate it and even remember the food itself as being inferior.
If you want a nice, quiet place to talk over dinner and sit back, relax without diners in flip flops and park clothes, adequate spacing and such, then Le Cellier is everything but that.