We stayed at this RS-recommended family-operated hotel for Christmas markets in 2019. Friendly, helpful staff. Comfortable rooms. Elevator goes to reception / breakfast-room floor -- I specifically asked for a room with elevator access; we saw others negotiating a staircase to an upper floor. Ample traditional breakfast with eggs boiled for you. Many juices, meats, cheeses, pastries.
Wonderful location right across from Hbf, great for day-trips. Short flat walk to Christmas markets and cathedral. Longer (but manageable) walk to castle.
We had stayed at the nearby Ibis on a previous trip, but this location had much more charm. And better breakfast.
Agreed, we also stayed at Hotel Probst in December. Very convenient location for Christmas markets.