Stayed here for 1 night in mid April and enjoyed my stay, though I will say that this hotel is in dire need of a renovation in my opinion. It's not nearly as luxurious as I would expect for a category 6, and I stayed on a cash rate of about $350 USD. The rooms are very large, but it's a bit sad to see that this is one of the "most luxurious" hotels you can stay at in Hakone. It feels akin to an older Hyatt Regency in the US, but definitely cleaner and more taken care of. I booked a 2 Twin Bed Guest Room (they don't have King Bed rooms) and got upgraded to a Deluxe room, which is just a larger room. The 2 twin beds are pushed together to make a "King Bed", and they were relatively comfortable, but a bit firm. Bathroom was clean but had a bit of a weird set up. The shower area was certainly not as luxurious as other Hyatt hotels in Japan.
The shuttle bus is very convenient, but difficult to use as a foreigner as they request you to call the hotel to request the shuttle to pick you up from Gora station and Sounzan station...and we had data-only eSims, so no way to call the hotel. We ended up just taxiing to most places, but even finding a taxi in Hakone can be quite difficult.
The onsen was pleasant and generally quite quiet - there was only one person when we entered, and they left as soon as we got in. Only one other person showed up during our visit. It's hard to be in the onsen for too long as it gets quite hot, and it really doesn't feel any more special than a nice large hot tub. The area is clean and well taken care of though, and the showers were pleasant.
The food was far better than I expected for a western hotel in Hakone! The burger was one of the best burgers I've ever had, which is definitely not what I expected from Hakone. I ended up eating pretty much every meal at the hotel since it's not too easy to get around to the restaurants in the area - Hakone doesn't have great walking infrastructure, which was disappointing.
Overall, since it's the only Hyatt in the area, most people don't have a choice, but it's definitely miss-able as it's not that great of a hard product. Hoping they'll get a nice refresh at some point.