Good, if a bit strange. The Bourbon and lemon are what is most prominent. The mint takes a back seat, only coming if you keep it within your palate for longer. The dry vermouth is completely absent. I do worry for the balance had the dry vermouth been more prominent, however.
Which brands did you use? I had a different experience... Tried this twice, first using a cheap creme de menthe (a blaringly menthol, garbage drink), then Branca Menta (better, but still repulsive).