This hotel would probably be best for travelers with their own vehicle. For those coming by train, the hotel is about a 10 minute walk (for two active adults) from the train station along the river, not actually towards the village of Karlstejn. From the hotel, walking into the village takes probably about 25-30 minutes, but it is a lovely walk.
The hotel itself was lovely, with beautiful rooms. Ours had a view over the river. The slight seclusion described above did add to the feeling of romance. Be advised that the sauna facilities listed on this site are not included in the room, and the receptionist told us that access to the "wellness center" was the equivalent of $100/hour. The hotel was great even without it.
The breakfast, which was included, was pretty spectacular- not the typical buffet, but an actual menu. We had fresh fruit salad, beautifully presented, fresh bread, eggs made to order, and crepes with jam, along with fruit juice, coffee, and tea.
As for Karlstejn itself, if you're interested in visiting in the off season it's helpful to know that most shops and dining options are closed, and the castle is only open weekends.