I got a Ryzen 5 chip with built-in radeon vega graphics. It has 8 cores and is 3 times faster than a 2 year old AMD chip. The kernel 14.16 was having lots of troubles such as giving me that flash of junk on the screen before login and always freezing if left alone for an hour or two. The new kernel is blessedly problem-free. I still haven't tried the power management, which didn't work at all on 4.16.
This is a lesson on what to expect with new stuff. I'm amazed that improvements came so fast.
ps. darn, still freezing.