Since Apple updated their mobile operating system to iOS 9, the app lacked transit functions in major cities. They have added it now. Google has had this feature for a while. With Siri’s abilities also dramatically increased, Apple Maps has become a real contender in the space, and dominates in their handset usage statistics. More information can be found here: Apple Maps Vs Google Maps
While there are many other players in the field, many of them are being bought up and merging with the existing leaders in the industry. This is a highly competitive area, and things are changing rapidly.