I booked this hotel as an overnight stay with my boyfriend. We arrived a little early but they allowed us to check in ahead of time. There was almost no one there even though it was a Friday night. We found Atami beach to be a little crowded, so we spent most of the time at the onsen in the hotels. The view from all around the hotel is amazing. You can relax in the hot bath (It was fine even in August) and look out at the ocean for hours.
I think the best thing about it was how alone we got to be. We live near Tokyo station, so this really made the trip worth it. We were the only people in the outdoor onsen (where you can wear a bathing suit) and also in the indoor ones (which are separated by sex) the sauna was nice as well, and you can use massage chairs for free too.
Our favorite thing by far though was the delicious food that is included with the hotel. Both dinner and breakfast were fantastic and the service was great. The help was really attentive. I don't believe they speak English, but if you're Japanese is passable, they are more than willing to help. I'd reccomend this place as a quiet retreat for the weekend, but a longer stay could be a little boring. Also good if you want to go to the beach in winter, as the hot baths are so relaxing!