I was staying at the Mercure for one night in July 2010 with my wife. Overall, we didn't have so much to complain about, the Mercure Hameln is offering what you would expect from a Mercure hotel: clean and comfortable rooms. Nevertheless, we were in Hameln during the heat-period, with around 35°C temperatures. I was assuming that a Mercure would offer an A/C system, but unfortunately I was wrong. It was certainly 4-5 degrees hotter in our room than outside, really sticky thus! Although we left the door to our terrace open all night, we didn't have the feeling it would get fresher in our room. Consequently, we absolutely didn't sleep at night...
Apart from this, the usual problems with Accor hotels: every service costs extra: 16 € per person for breakfast (which is really exagerated!), internet etc. If you already pay near to 100 € for a standard double room, which I find a lot for a small city in the middle of nowhere, I would at least expect the breakfast to be included (or at a reasonnable price).
The location is ideal: very quiet, near to the theatre and a nice park and just 5 minutes walking to the historical centre.
If the wheather would have been "normal" in Hameln, our stay would have been ok. But due to the absence of an A/C, our stay was rather uncomfortable...
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC