Hi all, i own a 1DS 3, 7D and 1D4. The S is amazing. It has an x factor the others dont have. Its as clean as a whistle at 1600 ISO. I think the color renidition is excellent and way better than my 7D which feels like a toy in the handling dept conpared to the S. That said DXO sensor performance is pretty similar for the 5D's new and old and the S. Ive posted a few landscapes which i always use the s for, usually shot at lower ISO's. Portraits are amazing as the other guys say. Its built like a brick, really solid and its been dropped on a concrete floor twice, a rock once, been out in deserts, snow, rain and sea and still works %100 ok. Its heavy but thats what you expect, tank like build quality. The 4 is a different league again for sports but the s can do them all be it a bit slower. It will last you a lifetime.
Mick