Direct use comparison: it works a lot better. Navigating is much easier with the speed that it calculates...at the start of the route and mid-route, if you go off course. The option to pause navigation if you go off route is handy as well, so instead of a blank or frozen view, it continues to show your movement.

The other features you've described, like stamina and cycling ability, are interesting. Not what I'd call precise, but useful nonetheless. Just like the recommended recovery time.

As for grade detection, I'll be honest, all the complaining I see from people is confusing to me. Why are folks looking at their Garmin wondering the grade? Is there something magical knowing that you're on a 3% vs 5% vs 7% grade? I've ridden up a lot of steep hills, none of which has a consistently x% grade, and I don't need. a computer to tell me its pitched from 5 to 15 and back to 7, then down to 3. Just choose your gear, and keep pedaling, dammit.