Here's what Wikipedia has to say about Oroblancos:
"An oroblanco or sweetie (Citrus grandis Osbeck × C. Paradisi Macf.) is a cross between an acidless pomelo and a white grapefruit. It is slightly larger in size than a grapefruit but has fewer seeds and is sweeter. When ripe, its thick rind is bright green or golden in color. . .Oroblancos are round (or sometimes slightly flattened), with a thicker rind than grapefruit. When eaten, an oroblanco lacks bitterness associated with grapefruits and is rather sweet, but the white membranes separating the fleshy segments are bitter and usually discarded. Oroblancos are available from September through December. Their sweetness attracts many buyers in many countries, for example Japan and Finland, where the fruit is commonly referred to as a "sweetie." . .Oroblancos may be peeled and eaten like an orange, by tearing into segments, and are often eaten as a breakfast food. As a newly engineered fruit it remains a relatively expensive product."
I just tried one, and it's pretty good. Not as sweet as I was expecting (It seemed more like a cross between a grapefruit and a lemon to me), but still pretty good. The internet searches I did showed that one fruit has 200 calories. (And a ton of vitamin C, which is good because 'tis the season for catching colds!) The article mentioned that they're kind of pricey, which makes me even more thankful for Bountiful Baskets, because I get to try things like this that I otherwise wouldn't be able to!