Yes the performance per watt is impressive. But i don't really care to much for Performance per watt, because 90% of the time my card idles and i game the other 10%. I care about overall performance and to a lesser extent price.
So its impressive from an engineering point of view yes, does it make me want to run out and buy it - no.
Will AMD match Nvidias performance per watt this gen, i doubt it seriously . Will i care , no - not at all just as long as pricing is right and the vega card performs where i want it too.
The next generation we are going to get down to 10watt differences at 7nm or so and i seriously could care less even before then about power efficiency.
The only decent thing i see worth upgrading to in pascall is smp and the gains from that are no-where to be seen and won't be for a while.