The supported cities seem strange to me, however. In the US, the first two cities you would develop transit directions for would be New York City and Washington, DC, as they are No. 1 and No. 2 in train/subway use in the country and having by far the best transit. After that you would do the second tier of Chicago, Boston and San Francisco. Then you'd look into less transit-friendly cities.
Houston, which is pretty much a giant suburb, is a strange pick to go before more transit dense cities. I do see that the app makers want data in a public GTFS feed. But users won't know what that is. It's up to app and service makers to work with cities, not users. They just want something that works.
I say all of this, because the goal of any app launch should be to maximize user uptake and publicity. Skipping major transit cities like DC and Seattle for launch and instead including Houston, San Diego, etc. seems like a wasted opportunity. Shooting up the iOS most popular charts is the best path to success on iOS and city selection, and thus user availability, would be pretty critical here.