Much better AF, much better MF, better lens (shorter focus distances), better sensor, better menu, higher ISO, more megapixels, better button layout, refined body, faster operation, better LCD panels, more film modes. There's a lot to like. Of course, there's still always the unknown, but to me it sounds like the refinements probably outweigh the additional cost when I think about the shots I've missed over the last 1.5 years with my x100. Not enough improvement for me to make the leap, but for a new buyer I'd go with the "s". However, if Fuji comes out with a pocketable version of the x100s they can have my money again in a heartbeat.