Stayed during summer, so no idea how the place copes when it's packed with skiers...
Located way out of the way - good for peace/quiet, fresh air, and ski slope access (chairlift literally next to the hotel), less so if you need to duck out to a convenience store (nearest one is a full 4km away). Nearest largish town with shopping/eating opportunities, Aizuwakamatsu, is over 20km away.
Hotel restaurant requires a booking, and serves proper haute cuisine, with pricing to match. Worth it if you're not on a budget. Breakfast is fancy and varied, but very, very Japanese - don't expect bacon&eggs.
Rooms are huge by Japanese-hotel standards, and have stunning views out to Lake Inawashiro. Only thing to fault is a lack of powerpoints - there's only the one on the counter above the fridge, and another in the bathroom.
Top-notch onsen, with sauna and inside and outside hot pools, open around the clock.
Enthusiastic English-language support from reception and restaurant staff.