Essentially, what you have in the X100s is a tiny, super capable camera with fast, sharp glass that handles like a Leica M. The 16MP X-Trans chip is the best APS-sized chip I have seen—in skin tones, high ISO and sharpness. (They changed the distribution of the RGB pixels and lost the low-pass filter without getting moiré.) It is also insanely customizable. And silent.
Again, echoing Zack Arias here when I agree that Fuji is the new Leica. As someone who used many different Leica M film rangefinders, this thing is more Leica M than any digital camera Leica has made yet. By a long shot. And at a small fraction of the cost. If you woulda just used your film M camera with a 35/2 lens permanently on it, as many did, this is your camera.
The sweet spot with the X100s is to shoot on (L)100 ISO, at 1/1000th of a sec at f/2 with the built-in 3-stop ND filter engaged. That will underexpose full daylight. You can then overpower the sun with a small flash and shoot wide open in the process for gorgeous backgrounds at f/2.
Because of the ND filter, the equivalent exposure for your flash would be as if it were exposing something fully at f/5.6 at ISO 100. Doable, at modest range with a speedlight in an umbrella. And you can own the sun at any aperture with any monobloc.
Good review of the new Fuji. I have the older x100 and i love it more then any digital camera I have owned. The new one sounds like a hell of a update.