GPS units should work the world over.
Unless the batts are dead, or the unit is damaged in a fall, or it gets wet, or it's fairly cold.
That's the problem. They're reliable until they aren't. And when they aren't, they're a brick.
A map in a ziplock bag, and a good compass are a very durable system - Reliable in any weather.
(I might add that I actually have three compasses in my full outfit, as my belt, pack, and go-bag each have one, albeit that only the one in my belt is of a high quality)
I would say GPS is fine to carry, providing one also carries a compass and map for backup... carry both... Because electronics are notoriously incompatible with wilderness.
But my complaint is that GPS is too easy, so folks will tend to go that way, and forget learning navigation in the process. Kinda like how I can't remember phone numbers anymore, because the phone does that for me. I have lost the ability to retain them.