Mon Ami is one of my favorites and I usually go every time we visit Las Vegas BUT not sure if it was the Mother's Day holiday, the food was greasy spoon diner quality and the waitress had an attitude.  She did lighten up after the food was served and prepared incorrectly but still.  It was the letdown of our trip.  We will probably go back BUT only one more chance.  Hoping if we don't go during a holiday the service and food will return to the great quality it has been on other trips.