While going down I-12 in Louisiana, I was getting 150 megabits down over LTE. While the status bar said "5G" it wasn't actually connected to 5G... so it was just really good Carrier Aggregation LTE.
Using Safari on iOS, navigating to fast.com, which I suspect to be uninhibited, I got 1.8Mbps up 9.8Mbps down. This was with full bars on a 5G indicated cellular connection.
This is not a typo. Very disappointing. Cheap and unlimited, but clearly in the slow lane down here in urban San Diego CA.