I'm surprised that everyone is going for expensive bike computers these days. Am I the only one who simply uses Google Maps on their phone for navigation? I just look at the map with my eyes and then ride. If I forget where I need to go, I take the phone out and look at it again. Why do I need to have a map continuously in front of me? I use a Garmin GPS watch to track my path and ride statistics for later review. On the bike I use a cheap old computer just to tell speed and distance.
Phones can work, unless you need a waterproof case, thats an expense as is a decent mount. Battery life can be a problem, as well as screen brightness. I prefer to not use a phone but instead have one with me for emergencies. I also dont want my $600 iPhone on my bar when mt. biking. The apps are funky sometimes as well. Is why a lot of folks just prefer a device that is designed from the start to provide them with what they need out of a computer,