My group stayed there for a seminar in Dolce convention center, Bad Nauheim. The Hotel Johannisberg has only 9 rooms. My room was a traditional style. You will love it or hate it.
The shower booth is small, bed is small. The wardrobe is a standalone furniture in the room. Nothing is close to renovated, except a flat panel TV. There is no Wi-Fi.
There was an faint intermittent motor running noise around 5 AM. I was awaken by the noise and couldn't fall back to sleep.
The breakfast was acceptable.
I would find another hotel when I visit Bad Nauheim next time.