Transit is arguably one of the best apps for making your public transportation experience less hectic, and the app has support for most of the world's largest metropolitan areas. There's really no reason not to have this app if you ever need to ride a train or catch the bus. But recently, Transit received a huge update that not only brings its user interface design up to date, but adds a bulk of new features as well.
The update features an "all Routes mode," which lets users explore route and stops in their region, train and subway stations listed in auto-complete while searching, the ability to "search locations using stop codes," an improved offline mode, and more. Of course on top of all these goodies the newly updated app features a beautiful newly designed interface to flatten it up and make it more iOS 7-y.
You can get Transit on the App Store for free.