I was not impressed with GoPilot.
The free version is ok. It's a great mapping, planing tool but the voice direction is useless. ($9.99 extra)
With the Garmin you get clear advanced warning. "In 800 feet turn left on Main St."
Once you get there it says. "Turn left on Main St then right" letting you know ahead of time you better get ready for a right turn.
With CoPilot all you get is "Turn left". Heaven help you if there are two streets close together.
When driving down a freeway Garmin will guide you into the proper lane for tricky off ramps like an exit off the left hand lane. Not so with CoPilot.