DH and I have many Retreat sailings under our belt. Another on Connie coming up Jan 3rd. Tried YC for 4 days on the Seashore this month as an experiment. Decided its one and done. Physical spaces in YC were spacious and lovely, including cabin. Better than on Celebrity M & S class ships. But the YC food was not well prepared or of good quality. Staff tried hard but training was lacking. EX: Asked for ketchup to go with burger on embarkation day lunch - never came. Served pancakes on YC pool deck at breakfast, but requested syrup showed up 15 minutes later. One server in lounge barely understood English. All about training and management's failure to do so.
The YC enclave is very nice, but leaving it and entering the rest of the ship is a wild experience. Including the elevators, loud pumping/vibrating music and visual and sensory overload.
On Celebrity we enjoy the whole ship. Not so on the Seashore.