Although now that I think about it, Google Maps lets me down on vacation because I'm in unfamiliar territory and I have no idea how to correct for the mistakes it makes. When I'm at home (in Amsterdam) it makes plenty of mistakes too, but I'm familiar with them and the are, so I can easily correct for it.
For example, Google really dislikes the Sarphatistraat for some reason. It's a bike street: basically a gigantic bike path that also allows cars, but bikes have right of way. It's one of the most important bike thoroughfares in Amsterdam, so of course you should always take it. But for some reason, Google always prefers to send me along the Stadhouderskade, which is part of the centrumring for cars, one of the major car thoroughfares, parallel to the Sarphatistraat, and it does have a separate bike path, but you're still in car fumes. Also, it's slightly longer.
There are plenty of other bike routes it doesn't know. I should really try to get used to using Organic Maps on my bike from now on. It's excellent on bike and pedestrian infrastructure, including hiking trails, things to see, etc. Many years ago when I first learned about OSM, I was amazed about the level of detail I got when I zoomed in on Artis, the Amsterdam Zoo. You don't get that kind of detail on Google Maps. I really should use it more.