Mine differences: Bombay Sapphire, Foro Vermouth di Torino, Martini ,& Rossi Dry Vermouth. Meh. I like GM, but this drink doesn't do it justice IMHO. Perhaps the differences make a difference.
Liked it more on my second try. As Peter says, definitely showcases the Grand Marnier up front, but also some very nice herbs and spices on the after palate. I went slightly heavy handed on the bitters, which balanced the sweetness for me.
This is nice. You get the Grand Marnier (sweet orange cognac) up front, then the complexity from the gin, vermouths, and bitters fade in on the back-end.
This is different to the Alice Mine recipe in The Savoy Cocktail Book; that uses Italian vermouth, Russian Kümmel and two dashes of Scotch whisky. However, the above is the exact recipe for the Alphonso (Special) Cocktail there (also shown as the Alphonso in Boothby’s 1934 edition of World Drinks And How To Mix Them).