There were 120 guests, 3 restaurants, and 700 staff during our stay and you are paying for that roominess and exclusivity.
After you pass the other hotels across the street from Surin beach, you make a left past one gate and then the Chedi, then another gate before you arrive at the Amanpuri. Initially, the staff seemed politely distant, but after a few days, I felt more at home. We stayed in 502 which was 100+/- steps up from reception and the pool and between the buggy drops offs on the road, making it even quieter. I found it odd not to have a television in our room, but had no complaints otherwise and did not find the room dated. I was surprised to have a view of only the local foliage -- not distant water, mountains, etc. I had the best Thai massage at the Spa of the four resorts where I stayed and should have called ahead for the sauna.
The beach was what I expected in Thailand -- white sand and clear water. Lounge chairs on the beach were well spaced and often vacant and a drink or a 3rd umbrella were only a wave away. There were some small fish to be seen to the right around the rocks and coral, if you wanted to snorkle. Aside from an area in the cove past the Chedi, where they quitely sold food, drinks and trinkets, it was private and quiet -- virtually no longtails, jet skis, touts, massages, etc. The view from the gym at the top of the hill is spectacular.
We enjoyed the beach BBQ and particularly Stefan's ribs!! It included Maine, spiny and slipper lobster, rare jamon (fed on acorns for a year and aged for another 18 months), tuna, goat cheese, prawns, oysters, Thai specialties, salad, steak,...
For comparison, we took the buggy down to the gate and walked around Surin Beach. There were sunbeds tightly packed on the beach, bars, massages, sellers, and restaurants with an occasional topless woman who should have reconsidered. It was then that I appreciated the Amanpuri the most.