The Canon S1 iS is my third digital camera in five years. I love them!
Maybe four: I suppose my first digital camera was Canon's ZR25MC digital video camcorder. It had the ability to take digital photographs on an MMC memory card. The pictures were of low resolution (see photo at left; click for full-size 640x480 image) and the MMC card painfully slow. I noticed, however, that I much preferred snapping photos with the movie camera, than taking movies. That led to....
My first real digital was the first one capable of 2-megapixel resolution, the Epson PC800 (Aug '99). I was stunned by its capabilities, and I stil use it today for one very special feature: time-lapse photography. It can take as many time-lapse photos as fit on the memory card, such as 1,700 640x480 photos on a 96MB card.
But I was frustrated. The 2-megapixel resolution was too low and the lack of optical zoom annoying. My next camera was the Canon G1, because (1) I could reuse all the CompactFlash memory cards I had already purchased; and (2) it had the foldout viewfinder. The camera has been into Canon's Calgary (AB, Canada) repair shop twice: the zoom lever stopped working shortly after the warrenty expired; and I dunked it in the Pacific Ocean, after twisting my ankle.
But I was frustrated. The 3x zoom was too low, and the movie-making capability too poor. The dunking in the ocean was well-timed, for Canon just prior released the S1 IS. It has 10x optical zoom, and 640x480 movie recording of up to one hour in length (max of 8 minutes on a 1GB card; would need a 12GB memory card for 1 hour).
This camera has two "low" frustations: the low 3-megapixel resolution in this day of 4- to 12-megapixel cameras; and the inability to focus automatically in low-light scenes. OTOH, 3 mp is good enough quality for me (and allows more images per memory card). But I've now messed up too many shots, because of the camera's inability to focus on subjects.
Oh, and the flash is much better than on the G1 (more even illumination, less burn), but the flash seems to take much longer to recharges, resulting in missed shots.