Our stay at Adam's place was very comfortable. He is super quick to respond, and the place was setup extremely thoughtfully. We had plenty of hand sanitizer, and all the things you would need at the beach - sunscreen, beach chairs, snorkel masks, beach hats, ice-boxes, beach toys for kids - just bring your swimsuits and you shall be all set.
The kitchen had everything you would need for cooking, including all the condiments, seasonings, utensils, silverware, basically all little things that you need but don't remember when you are at the grocery store. He had provided ziplock bags for pack lunches, and shipping boxes to ship back souvenirs!
The only thing to keep in mind is that there is no air-conditioning, and it gets hot during the day, but the house had multiple portable window fans and we just put those against the open window and it cooled the place very quickly.
Another plus for us was that this place was walking distance to Kahalu Beach (one of the best places for snorkeling, especially for beginners) and a 15-minute drive to Captain Cook (rated 'the best place to snorkel' on Big Island), so we went for snorkeling every single day! And it is an 8-minute walk to Keauhou Bay, where most of the Manta Ray tours are, so we did that twice! It is about 20-minute drive to Kona city where all the restaurants and shops are.
Overall, a great place to stay on the Big Island, and we would definitely stay here on our next visit.