This is very very dry - I added more grapefruit juice and maraschino liquer - for my taste much better - but made from the book not online (no sugar syrup in book recipe )
Unless your citrus is very ripe, this cocktail is better with a splash of sugar. I'm continually retrying and updating recipes and this cocktail in our soon-to-be-released Sixteenth Edition has sugar syrup as per the recipe above.