that the sensor performance is reported to be the same or slightly worse than the G1X sensor is a bit disappointing of course.
It's the usual Canon Sensor story
Quote from DPReview:
"These examples (and our test scene on the coming pages) suggest that the RX100 II's sensor is so much better than the G1 X II's that it cancels-out much of the dynamic range and high ISO noise advantages that the G1 X II's larger sensor should bring...
Overall, though, the larger sensor in the Canon is much of the reason that the camera is so much less pocketable than the Sony, yet the full benefits of that additional sensor size are not realized: the Canon's image quality advantage isn't proportionate with its greater bulk."