Hi Sonia,
It's been a couple of years, but I've been to Sunset Waters. I went in late Nov 2002. I was travelling by myself, and the resort staff went way, WAY out of their way to ensure that I had a great trip.
I honestly can't say enough about the service. Jim, the manager, personally introduced me to other guests at dinner the night I arrived, which gave me a nice choice of being social if I wanted to be, or not if I wanted to be. I had someone to eat with every night I was there. Jim also lent me his car for two days to explore the island on my own!
As for the rooms - it's a simple resort. People looking for luxury probably won't like it, but the rooms are clean and plenty big enough, everything worked, and I had an AMAZING ocean view, with a private balcony. That's really all it takes to make me happy.
The beach is clean, the drink service was fast, and the drinks had plenty of alcohol.

I didn't take much advantage of activities at the resort other than snorkling because I'd lost my PADI card, but the divers I was hanging out with had nothing but good things to say about the dive operation. I went to something called the blueroom for some cliff-diving and snorkeling, and that was a lot of fun, I would recommend it. I want to go back and go diving.
The food was also good, but my experience was slightly different than average probably. I am a vegetarian, and when I told the cook that the first night, he told me he'd make me something special, so I got a special vegetarian creation every night instead of the buffet. The breakfast buffet was tasty though. The lunch pickings could have been more rounded out would be my only complaint there. Again, it's not "luxury", just good solid food, served by helpful and happy staff. Also of note, I mentioned I was there over the thanksgiving holiday. The resort is owned by several people, and the majority of them were there for thanksgiving. Some are from the States, some are from Europe. In any case, they'd all brought little touches from home, wine/herbs etc...and were putting on a particularly nice thanksgiving dinner for themselves. They invited me to join them, and I have to say, that was a 3 michelin star meal - best thanksgiving dinner ever.
The island, like the resort, is quiet, and the people are friendly. I found it extremely relaxing to go to the various beaches to take pictures and snorkle and read.
So basically, if you're high-maintenance or want a lot of activity, this place probably isn't for you. If you're just ready for some R&R, can take things as they come, and know how to be friendly and treat staff kindly...well, the staff of Sunset Waters will go way above and beyond to ensure you leave with a huge smile on my face. The only reason I haven't been back every year since is I haven't taken winter vacations.