Quite good! This will be sensitive to the specific mezcal used. I used Mal Bien 100% Espadin and it worked well. This is an artesanal but fairly tame mezcal. For everyday use I usually use Bulleit "95" rye but for this I used A.Overholt "Monongahela Mash" straight rye (95 proof, 80% rye, 20% barley malt, non-chill-filtered).
The wife and I, along with our Japanese friends, fell in love with this cocktail when we discovered Iwai "45" whisky from the Mars distillery. 80% corn, 20% malted barley, often compared to bourbon but I say that is ridiculous: if it can be compared to anything it would have to be a Canadian. The reason it works is its refined elegance, which allows it to harmonize with the other ingredients. This drink is a classy lady of great charm.
The impression this makes will vary enormously depending on the tequila used. With tequila Ocho it was sublime, with Sauza "Hornitos" it was good but not exciting. I recommend Dolin Blanc, as I don't think tequila stands up to the funkier Italian biancos. It's the same story with gin martinis.