I bought the 2021 Here factory update for my 2018 GMC Sierra 1500 Denali. It was $99. It took 45 minutes to install. You can drive the truck while it is installing. I update my factory GPS every year. Since I tow and have rear camera on my RV (one monitor connected) and TPMS (another monitor connected), I don't need a phone app running or external Garmin running at the same time cluttering up my interior.
I used the facory GPS on a trip and after a stop and a new destination was entered, the factory navigation screen froze. It did not respond to touch commands. It is always good to have a supplemental navigation app on your phone with you when this happens. I was able to use Apple maps to successfully get me to my destination. The GMC factory navigation screen returned to regular operation the next day.
Another really suprising thing, we just got a turnabout intersection in my town. On the day of the map update and while returning home, I went specifically to the turnabout and the map intersection had change significatly to mark me through. It wasn't a complete circle, but it sort of was there.
zoz