There're many things that you'd reasonably expect when you decide to stay at a castle hotel (e.g., splendid view of towns and villages, far away from any towns and driving to hotel at night or in poor weather condition can be quite challenging, you can easily find bats and mosquitos or hear the wolves howl). Other than these rather neutral factors, there are:-
The good stuff:
Staff really tried to be helpful (but are not very proficient in English); Very respectable "Customers First" approach (e.g., their bar virtually doesn't close as long as guests are still there and they won't take away breakfast items until they've ensured all guests are done with them); Offer late check-out; branded and quality bathroom supplies and everything (down to the cup of coffee that you get); Free admission for hotel guests to visit the museum (but be warned, some displays are quite disturbing).
Room for improvement:
Not much, but subjectively, they could further decorate the hotel to make it a little more luxurious which may enhance the experience that 'hey, I'm actually living at a castle'. Currently, they're using a "less is more" design concept.