In areas of congestion, 5G should be more reliable than 4G. Similarly, latency should improve. While it might not always make a huge difference if you're just checking email, but if you're reliant on cellular for real workplace usage, it might make a a significant difference. That is, if it's done correctly.
The other thing is that often times, at least early on after things have been properly implemented, those with the capability to take advantage of new technology get more consistent access than those with older technology, simply because there is less congestion on the new tech. With some of local carriers here, this is exactly what happened. After 4G was implemented, those with 4G phones had consistent access. That actually diminished over time, as more and more subscribers got 4G phones. Since then the carriers have been playing catchup. Yes, you could argue it's because the carriers aren't supporting 4G well enough, but the problem is two fold: 1) They have more incentive to invest in future technologies, not past ones, and 2) 4G doesn't handle congestion as well in the first place.
Latency definitely isn't consistently <40 ms when in congested areas.
The problem is people keep arguing about near-perfect 4G LTE vs near-perfect 5G. What they should be discussing is real-world 4G LTE vs real-world 5G. And in my neck of the woods, real-world 5G actually exists.