Made with Tippelman's falernum syrup, Appleton 8, and Smith & Cross, along with some demerara simple. Quite a tasty drink, the falernum neatly underscores the funky rum elements. I agree that the simple syrup is necessary to really bring out all of the drink's components, otherwise it is just too tart and one-note for my palate.
Tasty! Like most drinks with falernum in it, a quality one will make or break the drink, I find. On top of being prepared to adjust sweetness levels based on that falernum, I've also seen recipes modify the ratios of rum used as well, but 1/3oz Wray & Nephew seems right to me here.