This property is perfectly located walking distance (down a very steep hill) from Porto Ercole. We stayed there with eight people for a week in June. The pool is beautiful, and the views of the water and hills are more beautiful than the photos can show. The gardens/orchard are stunning and charming. However, rooms are smaller than pictured, and you should go expecting some inconveniences compared to US travel, and the place shows some wear.
The kitchen is well-equipped but small (really only room for 1-2 people cooking at a time), and indoor eating space is nonexistent (4 people only). But with lovely weather, you can eat outside every meal.
The main two bedrooms in the main house are perfectly adequate. The bedroom attached to the main house, behind the kitchen, is fine, with a more newly renovated bathroom, but doesn't attach to the main living area. Hot water is limited and shared, and you have to flick a switch to turn it on. All of this is fine for the adventurous traveler. Our only serious concerns were that the second building, where we slept 3 people, was musty and had some termite issues. So: 5 people can live here very comfortably, and enjoy the beautiful pool and surrounding area. But much more than that, and you'll have to decide that a few folks will be less comfortable in the out-building.