The first room I checked into (late, around 10pm) was the dreaded room 40. It's basically a cupboard right behind reception and is the worst room I think I've ever stayed in. Noisy, hot, cramped, and the only window leads right onto the street, so you can't open it for fear of being robbed in the middle of the night!
The next day some people had checked out and I got a decent room on the 3rd floor that had a fan! Thank you Cerano Hotel for moving me, this made the remaining 5 nights bearable. The room was basic, but the bed was comfy and although the bathroom was almost comically small, I was only there to sleep and shower in the morning, so it was fine.
The hotel offers a complimentary continental breakfast, which is decent - some nice meats and cheeses, and some lovely bread. Their coffee is very good, too.
It really is just a B&B though at the end of the day - no bar, no gym, and no frills. You sleep there, you have breakfast there if you're in a rush, and that's it. On the plus side, the cathedral (the Dom) is no more than a three minute walk from the B&B, and that's where you'll find the main group of bars and restaurants. Oh, and if you fancy something non-German, there's a gem of a British pub called Jameson's about a 2 minute walk from the front door of the Cerano B&B: the air con is working overtime, and the food is fantastic.
Overall: if you need a bed, there can be worse places (like room 40!), but it really is absolutely zero frills.