Yes. I stayed at Sandals in Negril.
Truth be told, I wasn't thrilled. I found everything to be merely OK (food, service, room, hotel grounds, etc). Nothing was horrible, nothing was fantastic.
That being said, if you want warm sun, sand, and quiet, and have few preferences about anything else, Sandals is just fine. It's perfect for the traveler who wants everything taken care of for them, but can't afford their own staff of help.
Frankly, I'm just not a fan of the all-inclusives. St. Lucia is such a beautiful place with so many great resorts that I would have a REAL difficult time choosing a Sandals property over almost anything else on the island. There are tons of great hotels and resorts in St. Lucia and I wouldn't rank Sandals among the top.
One of the best times I had in St. Lucia was in a vacation rental home right on the water near Pigeon Island (Rodney Bay). It was a small house with a fairly open floor plan, a small pool and private access to the beach. Included in the rate was personal chef who came and cooked us breakfast and dinner (we stopped at a market and stocked the fridge for snacks and lunches). It was absolutely incredible in that we just didn't have to deal with the hoards of people at those resorts and we had incredible privacy. The best part is that it wasn't much more than a stay in a low/moderate priced resort on the island. Here's a link to
VRBO's St. Lucia Listings (http://www.vrbo.com/vacation-rentals/caribbean/st-lucia - broken link).
Homeaway and other sites have good selection too. Next time I go to St. Lucia, I'm going to rent another house. I just can't imagine doing it another way. I don't think I'll ever stay at a Sandal's property again. But I do know plenty of people who will ONLY do all-inclusives when they go to the Caribbean and Sandals is among the best.
For full disclosure, I haven't stayed at the Halcyon beach Sandals resort which I'd imagine to be nicer than their Negril property.