I am not a portrait or studio guy. I shoot cars for magazines (and web sites, on occasion), which is almost always sunlight or available artificial light.
I am often searching for new locations and will drive around with the Powershot to take quick, non obtrusive snaps when needed, especially if it is private property such as industrial sites I am shooting because later I will need to go back and ask for permission. If I show up outside the fence with a big rig, I might get booted before I get a chance to say "Pretty please and I will take pictures of your heavy equipment for your use, too!"
I had a Powershot S1 IS for a couple of years before the S3. We also use it around the house with our young soon (soon to be joined by another midget).
But when scouting, I keep it handy in the car and it gives me enough manual control should I want it.
Cheers,
Terry