You can customize the cards before they reach friends, and you don't need to explicitly link apps.

This is bound to be helpful if you're a regular on both services, even if there isn't a huge amount of crossover between the two. However, there is a question as to whether or not it'll find much adoption. Instagram's music stickers may be easier -- it's simpler to start in the social app (you don't have to leave to find music), and you don't need to subscribe to a specific music service to soundtrack your life.