Dragonfruit is one of the more whimsical-looking things one can get at the market here.
Inside, it's kind of like a kiwi fruit, but a bit lighter and grainier in texture. It's sweet but can have an element of sourness too, perhaps depending on how ripe it is. Apparently most of the commercial ones are picked too early, so they don't reach full flavor. They're good, but maybe to get a knock-your-socks-off kind of dragonfruit you have to go to Vietnam, Mexico, or Central/South America, where they're grown, and get a tree-ripened one.