Canon G15 test result published at DxOMark Lab, The Canon G15 score is approx similar to Canon G12, the Canon G15 have new sensor and new bright lens but even the low-light score similar to Canon G12.
The new S110 uses same sensor as Canon G15 but Canon G15 scored 2 points less in overall score than the S110, take a look at scores and visit website (link at the end) for more details.
Source – DxOMark
Weird results. Maybe the G15 needs a firmware upgade?