The Canon S3 IS is a terrific camera.
But it has been around for over a year.

Sony is new..... an update to their previous H cameras and has had a year to add more featues.......and they have.

The Sony H7 has not been reviewed yet.
But it should be even better than the older H series.
There is a rumor that the H series is using a newly designed CCD sensor that produces less noise.
Since they have an ISO setting of 3200, there may be something to that rumor.

I notice that Sony added a lot of kick to their flash too. It certainly outdoes the S3 in that area.

Here is a link to the press release of the H7/H9:

Here is a side-by-side comparison of the Canon and Sony: