The Maps app has been going through some growing pains, but it has been getting better. Its upcoming iOS 9 iteration looks to be even better with the addition of a new Transit view.
The Transit view allows users to check out maps of metropolitan transit systems (trains, buses, subways, etc) for a number of major cities like Baltimore, Berlin, Chicago, London, Mexico City, New York, Philadelphia, San Francisco, Toronto, and Washington, DC. This means a direct line from Maps to a view of bus routes, subway stops, train times, and so on - no third party apps required.
Hopefully it's more accurate than Maps was when it first rolled out, but it certainly looks promising.