I'm pretty sure that the powershot s200 was sold as the Ixus V2 in Europe, in which case its the same camera that I've got.
Firstly, the proviso - I'm no camera expert, and i've only ever tried a few digital cameras.
Anyway, 1) the image quality seems superb. Pictures look great, and the colour is good. Especially once I junked the 8mb card that came with it and got a 256mb, so I could stop worrying about compression. Although to be perfectly honest with you, I'm not sure I can really tell too much of a difference anyway.
2) Easy to use? I can't fault it. Its very user friendly, the buttons seem to have a good layout, and I felt like a master with it after about 30 seconds.

It takes 1.5 seconds to turn on (As the lens extends from the case). It seems to take about a second to take a photo (not like my old mash the button down and snap 35mm) and the first photo you take after it turns on seems to take longer than the others.
The optical zoom is great, but the digital zoom brings in fuzziness.
Frankly its simple enough to use that my mother can use it, although I have to be careful not to say things like "press the button on the left" as she gets her left and her "other left" mixed up sometimes...
as for 3) and 4) Ive not tried it, so I can't tell you.
Basically though, it was a superb buy - worth every penny and more. It feels even smaller in the flesh than it does in photos, and the lcd screen is great. Its super light, you don't really notice you are carrying it (luckily it seems to take knocks well, as there are a couple of times when i really *should* have remembered I was carrying it). It takes some damn nice photos, and its functions are great. Can you tell I like it?
The only things I would change on it ,would be to give it a bigger optical zoom, and a snapshot mode, where it doesnt bother to focus, just takes a photo instantly. However, these are things i can live without. It'll be quite a while before i replace this camera!