The two bedroom cabin we stayed in was really big and had an amazing view of the lake. We stayed with our six year old and had a really amazing time. The oven and microwave are useful for cooking and there's lots of space for relaxing. I found the hotel was really quick on emailing me back when I had questions.
The hotel itself has a small shop (microwave pasta, a few tins, snacks, milk, coffee etc) that can see you through the first night, as well as small childrens' sleds that you can rent for about 50 crowns a day. The buffet lunches in the hotel restaurant are really good value.
Very few gotchas. We brought our own sleeping bags, pillow cases and towels to avoid a relatively steep charge for bedding and towels, and you're also asked to vacuum and mop the cabins before you check out, again to avoid a very steep cleaning fee. In our cabin the oven was on its own electrical circuit which needed to be turned on individually from an unlabelled timer switch in the porch – we needed reception's help to figure this out!
Would definitely stay again; incredible location.