I ain't got a G7 so I can't really compare with it though. In contrast to my early Kodak DX7440 it's average or may be I am still too early on my G9 learning curve that I don't get the best settings.
Here a shot I have taken without flash in my room around 10 pm with a minimum tungsten light
http://farm3.static.flickr.com/2247/1977059433_980700937e.jpg?v=0
If you use flash there is no problem picture come all right. Also note focusing dearly is much higher (against S3 IS) in low light conditions.