Should AMD and Intel be worried? No. The x86 architecture can handle a lot of complex instruction sets that isn't just possible with the ARM based M1. Apple Silicon, no matter how better it gets, won't be a threat to x86, at least in the near future.
Running iPhone and iPad apps natively is no surprise as the hardware is basically the same. However, the lack of a touch screen doesn't make a very good case for the usability.
What I hate is that Apple has locked out of measuring the clock speeds, power usage and temperatures. Hope that it is made available in future updates.
Things get interesting on the GPU side too. The GPU performs dangerously close the GTX 1050, which is very impressive considering the low CPU+GPU power envelope.
Having said that, the M1 is a very efficient and powerful chip. I'll be happy to see the M1 benchmarked with a standard test suite after a few months when the platform is more mature with more native programs/benchmarks.
But here we are. Extrapolating the data available, it can be inferred that the 4th generation AMD Ryzen U chips can perform around 1.2-1.5x (with a few outliers) of the M1 while still within the 15W limit.
Going through reviews, I see that benchmarks and even the competing hardware seem to have been cherry picked to highlight the advantage of the M1 chip.