huh? Did I missed something? It looks clean, and while not fancy, it's perfectly adequate for a Mercure (that are, at least in my opinion, a 4* chain on the lower end)
I've had Mercure hotels that had smaller rooms and/or were more worn / older furniture, and I'd NOT have called them to be the "worst" Mercure in the world..
edit: Checked Google reviews, 3.7/5. TripAdvisor is similar. Certainly not a great hotel, but FAR, FAR, FAR from being the worst Mercure.