I really liked this. The combination of the elderflower and lemon gave the cocktail a very refreshing grapefruit tinge to me. I do find elderflower a bit sweet, but next time I will use the larger flutes, the additional Champaigne lessened the sweetness for me, but we do like our cocktails a bit on the dry side.
Very simple but very tasty, two qualities I appreciate very much. The lemon provides a lovely aroma, while the elderflower magically turns my cheap champagne split into a honeyed luxury. I bet this would be a crowd-pleaser, and it certainly would be a cinch to mix and serve for a party.