William's place was great. It was huge, and had way more space than we needed for 2 people. The unit is actually in the Kona Coast Resort, and you do need to check in at the front desk before you're directed to your unit. The whole resort is spread out, so you may have to drive to get around depending on what building you're staying in.
We didn't really take advantage of most of the amenities like the pool, but they have a lot of things to do around the resort.
The huge king bed was very comfortable, and having 2 full bathrooms to use was very convenient. The living room was spacious with big couches, and the kitchen was stocked and we were able to cook a nice meal one night. For the price, it's very hard to beat and would easily stay again if I visited the Big Island again.
It's a little south from most of the main areas of Kailua-Kona but it was a short drive to get to most places.
The one con was that they have a daily charge to run the AC for $8.37/night. It can get hot inside the unit, so definitely recommend paying for the AC even though there shouldn't be an extra charge for it.