Anecdotal evidence, but I do use Apple Maps in Poland and they work just fine for me, I guess the mileage may vary.
They do work for me either, but I have learned to double check the locations of POIs with Google Maps to make sure I’ll arrive at the correct place.
So does my father - but then again, it is important to remember the context. It's not going to be an issue if you only drive in big cities or on main roads. The only time I really need to use GPS to navigate is going out into the complete boonies, and Waze does that expertly. Apple Maps, meanwhile, helps me remember my Mercedes' stock navigation, which is forever locked in 2011 and runs in 256 colors. :-)