Visited Giessen on a conference, so didn't have much time to look around or use the hotel facilities. But I was quite happy with the service I received. I arrived late, but check in was quick and friendly. I unfortunately missed room service (which stops at 12:30), but the pleasant bar was open until 1:00. The room was very large (for a single) and well furnished. Check out was again quick and friendly and they called me a taxi which arived in a few minutes.
