You can use Lost Mode to track down your iOS device and shows its approximate location on a map, much as it always had.
If a thief wants to try and disable Find my iPhone, or wipe the phone to disable tracking, the activation lock will force them to enter your Apple ID and password first, and if not entered, prevent any software tampering with the tracking.
If you remotely wipe a device, you can reactivate it using activation lock and your Apple ID and password as well.