I'm in the Air so the UI is slightly different but the routing is (or at least should be) the same.
I find it...moderately okay. Not the best I've used (Waze in its pre-Google Days) not the worst either.
My main issue, other than the fact that it REALLY, REALLY wants me to take expensive express/toll roads even when it wouldn't save any time or distance, is that it occasionally takes me on unintended adventures.
For instance, when leaving my wife's work, it consistently tells me to take an impossible left turn, despite the median in the road preventing anyone not in a truck from doing so.
Or on my current road trip it routed me off the main highway into a rural/county road. I assumed that it was routing me around a traffic slowdown (like Waze) as I could see that the router would have me rejoin the highway about 25 miles later. At first it seemed fine, a nice 2-lane road with rural residential properties and a few small businesses. Then 7-8 miles in, the road suddenly changed. It got a little narrower, the lines went away, and there was a "rough road" sign. I could see on the map that there were some side roads that looked like they would take me back to the main highway, so I continued, and the road wasn't that bad, just a ton of patched former potholes. Then a few miles later, there was a sign that I didn't know what it meant. It sais "No traffic coverage". I asked Google about it And learned that it meant that you weren't supposed to be on that road unless you were a resident. However, by this point on that road all of the residences had disappeared, and there was absolutely NOTHING. I proceeded cautiously thinking I'd take the next side road back to the highway, only to find that the side roads were ill-kept dirt roads. At that point my choice was to either proceed cautiously or backtrack 10 plus miles.
I decided to risk it and continued. The road did eventually me to the road indicated by the routing that would take me back to the highway, given the nature of the road, it was entirely possible that it would have dead ended or become impassable before it actually connected to that. I got lucky.
But it was a mildly stressful situation, and I really have no idea why it decided to route me that way.
Other than that, MOST of the time the routing is fine. Not necessarily the quickest or most efficient but sufficient.
I believe in the Gravity/3.x version there is more customization of desired SoC at destination/charging stops, but even without that in the Air, the Charging stop planning is fine. It seems to aim for about 20% SoC for charging stops and 15% for final destination. Though it does seem to like to choose Tesla which sucks for an Air stuck at 50kw, but that is much less of a problem with the Gravity. Plus maybe (I'm hoping) the 3.x version is better about actually following the charging vendor filters during automatic routing because in the Air it seems to completely ignore that.
The main reason I continue using it, is because the interface is quite nice and readable along with the dual-screen capability and, because of the limitations in place from Google, and the size and shape of the top Lucid screen, running Waze in Android auto is small and difficult to read.