Stayed here for a week in late March. We're two families from the US who had never visited Engelberg.
The house is a one mile walk from the train station which is a lot with a full complement of ski gear. We walked because there's no bus service near the house. In retrospect, we should have gone right to the slopes and rented a ski locker (go to Stockli's rental for a GREAT locker) so as not to carry all our stuff up the hill to the house.
Our two families (8 total) really loved the house. A very nice kitchen with all the latest amenities (we cooked every night), an awesome sunroom facing the mountain with a heated floor (***** stars!), a Living room/TV room with plenty of room and bedrooms for everybody. We didn't even open up some of the bed rooms. There were two master bedrooms upstairs and at least four (maybe more) bedrooms downstairs with at least two bathrooms down there. All furnishings were fine and comfortable. We never ran out of hot water. the house had a washer we used frequently (line drying). The fireplace was also nice.
Only thing holding it back from five stars is the lack of a hot tub and the walk up and down the mountain (we got used to it quickly though). We didn't have a rental car, but there is parking at the house (and free parking at the ski resort).
Skiing was fantastic and affordable by US standards.