Did not make this with egg white (I usually don't first time trying a new recipe). Without it, the trusty ratio in these specs yields a boldly-flavored, more than satisfactory drink. Arguably lacking a little acidity and/or (as Sean noted) a hint more of alcohol. Didn't sound pleasing on paper to me, but I was thankfully surprised with its quality.
It’s nice, and the combination of elderflower liqueur and orange work well together, but it needs a kick of alcohol. Vodka or gin or tequila. It’s very tame.