I can understand the jam thing but the weird route thing is crazy, especially because that route often makes you spend more time not less. It prefers weird backroads with lots of turns instead of straight larger roads (and that's stupid) but a thing I noticed traveling a lot for work in a hilly area is that it doesn't seem to take road pendency into account. Sometimes it makes you go up and down a hill instead of staying in the valley road that goes around it: it take twice the time IRL but is like it thinks "whoa, 5km instead of 7, that's a great optimization" and that's incredibly stupid.
Apple maps is more conservative and tries to stick to larger roads if possible only sending you into more obscure ones if it is very convenient.
Another thing is that Google Maps is really aggressive on labeling something as a road: sometimes they are off roads, tractor paths or large trails that a car cannot travel on but it doesn't care.
Those are my impressions traveling mostly in Italy and bordering countries.