The island has been a tourist attraction for decades, but it is not a typical charter destination. This is a place for travelers that want to rent a car and explore the island themselves.
And there is a lot to see!
In the north you find the posh areas of Costa Smeralda. Here you have perfect white beaches and can go spotting for the rich and famous that go there for leisure. The little town of Porto Cervo is packed with yachts and luxury shops. But the town itself is super nice, not flashy, and definitely worth visiting.
On the west side of the island you can visit medieval towns with narrow streets almost unchanged since they where built. Walking in there is like stepping back in time. And this is really where you find the real charm of the island, I think.