It's open source, development is very active, and there's much more of a focus on user experience (2/3 of the pinned issues).
Though it does notably lack public transportation routing.
It doesn't show you as much detail as it could. The color scheme has a poor contrast. The colored zones are ambiguous and often misleading. You see a random-looking sample of points of interest rather than a consistent listing of every single location of a certain category and significance. Major roads and streets are easy to see, while railroads fade into the background. And sometimes you can see major bridges only by zooming in, as Google Maps thinks they must be insignificant because you can't drive over them.
This is true specifically for cars and maybe mass transit. But for navigating on foot or bicycle, OSM is much better. OSM tells me where water fountains and park benches are, and has far more trails marked. Google Maps excels at leading people to places they might spend money, and is mediocre at most anything else.
Of course, you still need country-specific code to account for all the various abbreviations, e.g. Str. in German, or the cardinal directions and road type abbreviations common in the US (blvd, hwy, dr, etc. ... I've recently fixed a bunch of those in OSM and it's quite a list). Well, and checking alt_name, local names and names in other languages in OSM as well.
Bike routes "work" at best.
I actually find Google's routing pretty frustrating. Maybe in cities you want the shortest/fastest route given the traffic, but outside of cities other factors are at play, such as road quality (ie width, straightness, max speed) and directions simplicity. The usual "one size fits all" approach of Google is sorely lacking. Map routing is crying out for customizability.
It was worse when Google Maps tried routing us around traffic by sending us off the highway and down on narrow roads through neighbourhoods and side roads. Poor people living there suddenly had a main road along their homes. This kind of thing should be regulated.
Anecdotally, a friend of mine in Oklahoma says he never uses Google Maps to navigate because it has a bad habit of trying to route him down unimproved ranch roads of dubious quality.
Personally, I usually prefer Apple Maps since it plays nicer with CarPlay, and while Ohio has fewer roads of dubious quality like that, my experience left me much less trusting of GMaps.
I've been working on a faster OSM plotter for a while now, but the data format is really a pain.
I don't know how accurate it is compared to the tons of Android smartphones sharing their location to Google, but in areas with many Tesla it is good enough.