We didn't like leaving!
There isn't a lot of on-site parking, but worst case is the public car park (also free of charge) which is about 100m. Not a deal breaker, just a slight annoyance if carrying sleeping toddlers.
We had three nights in a Tower Room (split over two levels) and a fourth night in a Standard room; both were excellent, but next time I would choose the extra space and practicality of the Standard room over the "romance" of the Tower Room. But the kids loved both, and I would happily stay in either room style again.
The breakfast buffet was very nice: diverse without being overstretched, and more than enough of interest for adults, tweens and toddlers. Good quality, well prepared and attractively presented.
The staff were superb: great service and really friendly (reception, breakfast and cleaning). We had initially booked for two nights, but were so impressed that we extended for a further two nights after our first breakfast. Apart from having to change rooms for the last night (due to a prior reservation), no problem whatsoever; we simply spoke to reception and they were happy to accommodate us. (You may take such a flexible attitude for granted, since the hotel is charging money for a service, but in Germany that is... not always my experience!)