I'd like to begin this review by saying that among the hundreds of hotels I've stayed in this is absolutely the worst. Your experience may vary, but here is mine:
1. I was surprised that I got a single room, but thought maybe I clicked the wrong button during the reservation. Only when I checked hotels.com did I realize I was 'downgraded' without notice.
2. I reported this to the reception the next morning, and while one of the women was fine the other was rude. Eventually, I had to pack up and leave the hotel in the morning and check in again in the evening.
3. For the first mistake, the not-so-unfriendly woman offered to give me not to charge for the breakfast. As I checked out, I had to pay 30 euros for the breakfast. I didn't bother to argue with the rude blonde (who checked me into the single room and was always apathetic and unwelcoming).
4. The room card stopped working after the second night (only worked for one night) because they thought I would be leaving that morning - great.
5. There're only about 7 free parking spaces. You'll have to pay if you park in the underground garage, even though in the German brochure I'm sure it says guests can park there for free (my German is very poor, but 'kostenlos' and 'tiefgarage' are pretty obvious).
For all these, I've got only one 'sorry' and still had to pay for the ‘free’ breakfast. This hotel is an absolute 'best to avoid'.