I travelled with a group of around 30 snowboarders and we pretty much took over the hotel. I found all the staff made you feel at home and welcome as you walked in through the door and throughout your stay.
I would agree the rooms are a bit basic, no WiFi, No tea and coffee making in the room, however most of the day I was out on the slopes, the evening in the bar and it was nice not to be checking emails!
Set menu for the the week, but they will make changes if there is something you dont like.
Niderau itself is quite small if your more than a learner so I would suggest going to some of the larger places by FREE ski bus about 30mins away
Overall the place is clean, warm and friendly - what more do you need?