Wow! I am sooo glad that I found this place! On our last trip to Hawaii, we went to Oahu and stayed at the Turtle Bay Resort on the north shore. We loved staying there. It's a beautiful property. When we left, my wife said "let's come back to Turtle Bay for all of our vacations." We really loved staying there. After staying at the Waterfall House, I doubt we will ever go back to Turtle Bay.
When we walked on the back decks for the first time, we were simply in awe of the stunning view of the ocean and of Hanehoi Falls. Pictures cannot come close to doing justice to this setting. We settled in and had a relaxing evening. In the morning, we watched the sunrise from the master bedroom. We then decided to continue watching the sunrise from our private hot tub on one of the decks. While we did the Maui things (Road to Hana, Lahaina, snorkeling, relaxing on the beach, etc), we ended up spending 2 full days in the house, on the decks, and in/around the pool. Having a very private pool completely to ourselves is so different than sharing a resort pool and hot tub with hundreds of other people.
To be clear, staying here is very different than staying at an upscale hotel. We have stayed at a number of 4 and 5 star properties over the years. For example, the Montage Deer Valley is an incredible hotel. We have loved our multiple stays there. Again, this is very different than that. If you demand world-class service and high-end furnishings, this might not be for you. The kitchen doesn't come with a Viking or Wolf stove, a big stainless refrigerator, etc. But the kitchen had more amenities than we expected. It had everything we needed. Pots, pans, plates, glasses, utensils, spices, etc. We bought some nice food when we arrived, and enjoyed some nice dinners at home. If you want to exit your hotel and immediately have lots of restaurants within walking distance, don't come here. Go to Lahaina or Wailea instead.
Regarding the privacy, you can't see or hear anyone from any of the decks or from the pool area. It would be easy to spend several days without seeing anyone. My wife keeps the windows & blinds at our home closed as much as possible. She was completely comfortable with the amazing views in all directions.
You will need to rent a car. Once you turn off the Road to Hana, you will end up on a bumpy dirt road, but any rental car will be fine getting to the Waterfall House.
For a romantic getaway, I can't imagine a better place than this.