Recently spent two nights here near the end of June (midweek). Rates were good at around 18k JPY including breakfast and I'd say this is pretty good value for this time of year. I'm not a Hilton elite, but probably would have felt even better value with elite benefits. Things were a little quiet, I don't think they're in full-on summer mode yet, as none of the summer activities (zip lines, walking trails, adventure courses etc) were open yet. Golf seemed to be the main activity for guests, not too expensive either at this time of year, around 7500 JPY per person if in a group of 4. There were also some rather large school groups staying too. You'd probably want to have a car and plans to do things around the Niseko area if staying here in summer, there's nothing within walking distance although you could take the shuttle bus into Hirafu town. That said, if you just wanted to chill out at the hotel during the day it's nice and quiet, and the onsen is uncrowded.
View from room on the 10th floor
Golf course looking pristine
Was impressed by the number and quality of staff here given the low season, staff members from all over the world and everyone super friendly and helpful.