Interesting comment regarding Transit - as a Londoner who went to NYC for the first time last year I didn't even contemplate looking up another app; I just opened up CityMapper and it said "It looks like you're in New York. Switch City?", so it's pretty seamless.

A few years ago I'd definitely have trawled the App Store and I'm sure I'd have found Transit, but it just goes to show the power of a good, reliable interface and considered rollout to ensure you're always the go-to product if someone is aware of you.