I had an excellent experience mostly with the hotel, but once in the restaurant (both are dog friendly).
I was lucky enough (and very grateful) to be upgraded to one of the rooms in their adjacent, newer building (just across the road). Entry to this building is secure and can only be accessed by your room's keycard (which also allows access to the reception area in the older building). This new building also features a small, modern elevator to get to the upper floors...handy for me as was on the top floor.
The upgraded room I was assigned to was immaculately clean, very spacious (bathroom too), and furnished with modern furniture, bed, and large flatscreen TV (Netflix app is available). It was an open planned designed with lounge/sitting room combined with the bedroom (containing a very comfortable, soft yet supportive, King mattress). The lounge area contained a sofa bed and matching chair, plus a sitting chair. The room also contained a desk with a chair, a small mini-bar fridge (stocked with drinks and snacks), a large mirrored wardrobe, and a luggage rack, with two bedside tables next to the bed. Heating was provided by either an air-conditioner or by two separate water radiators - these radiators performed very well. The two large windows had curtains and electric outdoor blinds for privacy at night.
The bathroom was very bright and well lit, had a heated floor and towel rack, large vanity mirror, and a large walk-in shower (excellent water pressure and hot water supply).
As I had to extend my stay twice, the last few nights I had to move to another room. This was much smaller (bathroom as well), but the quality was still the same, as to the cleanliness. The only downside to this other room is that the TV did not feature the Netflix app (and the vast number of channels available were mostly in German....or German dubbed).
Both rooms and throughout the property (and between buildings) had good WiFi with a constant and strong connection.
I only dined once in their restaurant (dog friendly too), and both the meal and the service were excellent. The restaurant with a bar was very comfortable and provided a good atmosphere. When the weather is warmer, they have an alfresco section, which would be nice to dine at during summer. The menu had a good array of entrees and main fares, with a few dessert selections on offer. The quality of my meal was superb.
The only negative thing about the property is that there is only roadside parking. This can be hard to find during the daytime due to nearby business/hospital, but after 5pm, parking was a bit easier to find nearby and/or opposite. (NB: During the daytime parking was easier to find further down the one-way street or in neighbouring streets).
The location is quiet and not too far away from the shopping precinct of Bad Godesberg- only about a 10-15 minute walk. The castle is an easily walkable distance, too.
I can highly recommend this excellent hotel/restaurant if you plan on staying or dining at Bad Godesberg.