It can be interesting. On my recent trip through a lot of the Rockies, it should have been perfectly happy to stay in 5th (CVT manual mode) and keep the speed or slightly lose speed, and drop to 4th on steeper parts. It wasn't, often it would drop it down to 3rd for short bursts to get the speed back up.
The CVT is pretty good, but it has a few quirks that the manual mode is useful for.