Depends a bit on what kind of routes you’re following. You can have a basic device that gives you speed, distance, breadcrumb trail or left/right and an alert to say of you’ve gone off track. Those are great as long as you’re follow a relatively obvious route, and you don’t have a reason to deviate.
Where they’re not so good is when your route takes you through a common or woods where you have multiple intersecting paths, it can be quite confusing to work out which is the straight ahead/slightly left turn, and you might have to try a few to get far enough up the trail to see if you’ve take the correct route or not.
Or if you have a mechanical/injury/weather complaint and you need to cut your route short, find some food/shelter, dow a bit of route planning on the hoof, you need something else with you, a phone (with maps and/or signal) or a map.
I’ve got an Oregon 650 which is a bit old and clunky, but it does what I want it to, set it up in lots of different ways, I can load custom maps, replace AA batteries on multiday hikes/bikes/skitours.