I didn't realize it until some CPN reading, but the G7X II offers some IQ enhancement over the G7X...
Inclusion of diffraction correction, improved metering (superior to the EOS M3) and an additional stop of IS due to enhanced logging input from the gyro sensors as the DIGIC7 can handle the additional data logging. Even though it uses the same sensor and optics as the G7X, it should in theory produce better IQ as diffraction is a very real problem on the G7X, also it being so small and lightweight, IS is a problem too. Metering has always been a PowerShot weakness, if they've surpassed my EOS M3, this should be good.
The AF system has been enhanced; low contrast or similar contrast situations have been improved, as well as subject overlap, I've personally observed the AF confusion phenomena the G5X/G7X so if they've improved it, which they say they have, this is great.
The continuous burst is now 8FPS, raw (finally).
They've reduced screen refresh latency by 50% making the touchscreen "real time". It's marketing fluff, but 50% latency drop is good stuff.
Lastly blackout time has been reduced by 50% as well, I can't say I've observed blackout on the G7X/G5X as I've only played with them at BestBuy, but this is always good. Boot up times have also been reduced.