Location is quite good but avoid to stay there in summer.
There is no air-conditioning at all!
Formerly the hotel was an hospital. A lot of coach tours are staying in the hotel! It feels like a nursing home while they are storming the buffet.
Request for a late checkout after 4 nights in the hotel, I wanted to keep the room until 1 or 2pm while the checkout time was 11am, was denied. They wanted to charge me the day rate to keep it.
Would not stay there again for the room rates they charge. 50% off would be adequate.

The main building of the Hotel Residenzschloss is an impressive
old classical building, situated opposite the beautiful early twentieth century city archives (Stadtarchiv), the rooms are situated in a modern building. At the end of September 2005 we made a "cheap" Internet booking for a non smoking "standard room" and were pleasantly surprised to find out that it was a spacious room with a sitting corner, a large bathroom and a lovely third floor side view of a nearby river.
Plus points: central but quite and green location at the foot of a hill towered by an old abbey, extremely friendly staff, very good breakfast buffet (including a large choice of tasty fruit juices, smoked salmon and German sparkling wine). The hotel has two restaurants and a hotel bar and a new sauna and fitness area (bath robe and towels provided). We took advantage of the possibility to rent a bicycle for the day and didn't even have to pay!
An additional bonus is the nearby Pelikan, a pleasant "Kaffee" serving tasty asian food.
Bad points: none we could find.

Hotel Residenzschloss is a big place, made up of multiple blocks joined by glass walkways. Its big enough to hold conventions, so expect large groups of businesspeople.

We stayed in one of the modern blocks and the room was good, clean and quiet.

Plus points: easy parking under hotel, location (by old town underneath the sublime monastery), nice terrace to sit outside on and a good breakfast.

Bad points: no air conditioning, bed was 2 singles joined together, shower was over the bath (I just hate that) & no views from rooms.