This is one of my favorites. It is utterly simple and elegant, and it relies 100% on the quality of the ingredients and a light touch.
All you do is rinse a glass with bitters (if you look closely at the photo, you'll see streaks of bitters on the sides of the glass), and then add some quantity of gin. That's it. No ice, no ceremony, just two perfect ingredients evoking a whole cloud of sensations.
The gin you use and the bitters you use determine the character of the drink. The only other variable is how much bitters you use, determined in part by the shape of the glass.
I always use a small snifter or a sour glass, because an ounce and a half to two ounces of gin is plenty. It is a potent cocktail, because the gin is not cut by anything, including water from melting ice.
When this is made with Angostura bitters and a traditional London dry gin like Beefeater or Bombay Dry, I think it smells like Christmas. Make it with one of the richer-flavored pot-still artisanal gins like Ingenium Gin or cold River Gin and it gets much more complex and earthy, and delicious. Try orange bitters and Rangpur gin for a light summery ethereal citrus thing.
One of the best things about the Pink Gin is its simplicity. If you go to a restaurant with a mediocre bar, as long as they have gin and bitters you can explain the very simple concept and have something to linger over while your partner finishes dessert.