We went to Koh Samui last week and stayed in Six Senses for two nights. The resort area is not as remote as we thought, the hotel also offers complimentary shuttle bus services to Chaweng Beach and the Fisherman Village, although the schedule is not frequent so we have not used this free service. Most of the time, we just stay in our villa with nice ocean view. The most impressive of this hotel is the restaurant, "Dining on the Rocks", the food is really good and not very pricey compared to a fine-dining in Hong Kong.
However, one of the problem is the mosquito! The entire area is full of mosquito! Although, the hotel already has many measures to fight against the problem, i.e. with mosquito kit every where and mosquito repellent spray and lotion for you, we still got bitten hard by them. My hubby got at least 20 bites and me more fortunate 10 bites! I really feel that the entire area is not fit for human beings to live in .... Also, there is a construction site on the East side of the Island, I recommend you to request for a villa at the West side.
Other than that, the service is excellent and impeccable. However, I guess I would not go back to this hotel because of the fierce mosquito problem.... unfortunately.