Totally empty during the weekdays, you can have it for yourself. At weekends locals come to chill with families. Sand is nice, clean and water pleasantly warm.
Probably my favorite beach in Ko Samui. Very clean, the sand is soft and nice for the feet. Not many tourists and there are some restaurants where you can eat delicious Thai food.
Lonely Beach is not a lonely place at all! There are loads of bars, you can choose from any type of cocktail you can think of and enjoy the night. Many people come over, easy going and chill atmosphere.
It is long indeed. 7km of sand and plenty of space for you! At one end there are guesthouses and at the other there is a path for a jungle trek from the ferry.