I have eaten twice at Chez Dumonet in the last year. Our experience was entirely different from the one reported. The food was excellent both times and the service was unusually attentive for a Paris restaurant. The waiters we had were very helpful in helping us decide on the amount of food to order. For example, he told us that the pate would be enough for our party of 4 and it was perfect. He also helped select the appropriate side dishes and recommended the souffles be ordered for two which was perfect.
In each visit, once with two friends, once with our son, we had great food and superb service.
I am sure the reporter above had a bad experience and I am not defending the restaurant, but it was nothing like our experience either time. It is our go to place in Paris for Beouf Bourguignon -- I even ordered a full order when dining with my husband and son because they wanted to order other things and also sample the house specialty. The pot served three generously and they also enjoyed their duck and steak.