After owning Olympus and Sony digital cameras for years (since 1998)the S1was my first Canon digital camera purchase. I purchased this camera for the 10X zoom and IS and to use to take photos at Sci Fi cons and zoo trips with my kids. But to be blunt, this camera has the worst/bumbling/most annoying autofoucus problems of any digital camera that I have ever had. I have three different Olympus ultra zooms that have never had any problems focusing, yet this Canon camera hunts an pecks and sometimes refuses to focus - partcularly in low light. (Canon has no focus assist for low light which is an really dumb omission.) The focus gets totally lost after a fast zoom too.. another problem I never had with any Olympus Ultra zoom. Plus side by side..the Olympus ultrazoom pics are better exposed and have better color and contrast. The *only* advantage this Canon had was the IS and it uses AAs instead of a proprietary battery.
So I bought a Panasonic Lumix FZ20 (and recently a FZ5 for overseas travel :-) and both these cameras simply blow the Canon out of the water. The colors are better. The focus is lightening fast even in low light and after any speed zoom. The zoom is 12X. I have both the Panys and the Canon, and the Canon is a piece of finicky aggravting ***junk***. Honestly it's most the ***annoying *** digital camera that I have ever owned with having to constantly nurse a woefully inadequate autofocus system along. I wouldn't buy another IS untrazoom from Canon if they paid me to. Not after the crappy S1.