Until there's some way to do a low-power display on a phone, I just don't think phone apps will ever replace dedicated cycle computers. The problem with phone-based cycling apps is that the phone's screen consumes a lot of power and thus drains the phone's battery very quickly (especially if WiFi and Bluetooth are enabled). I use my Garmin 830 primarily for navigation on my rides, which are typically several hours long. Using my phone for navigation doesn't work as the battery doesn't last long enough and if my phone goes dead, I have no way to call anyone in an emergency.