I really liked this hotel and the city of Heidelberg (although the hotel is ~40 minutes from the town centre by bus) but the cleanliness of the room was a bit of a letdown: the sort of cleanliness where you don't bother complaining to reception because it's only a stray hair on the sink or a bit of rubbish under the bed, but then you go and write a slightly negative review about the place online afterwards.
Seriously though, the staff are lovely, the food is good, and the rooms are comfortable and quiet. Apart from one stray hair and an errant bottle cap, the only thing I could find to fault is that the curtains are too small for the windows and I only discovered the blinds the next morning.