I've used osmand+ for 6 years nearly every time I drive. Its definitely usable and only craps out once in a while. The biggest pain is just lack if address resolution, but that is expected with osm generally. As long as there aren't walls between you and the satellites, at most I've waited a minute or two for position lock. Google Maps will use GPS and nearby WiFi to locate you, so its faster. Been playing around with Organic Maps lately and it has been nice, but I miss the advanced features and visual info elements osmand+ offers.