S100 has the lens ring that allows you to dedicate it to various functions ... like exposure compensation. That alone makes this camera wonderful. But overall, I have yet to use a camera at this size and weight that takes better photos overall.
The Panasonic DMC LX5 takes better landscapre photos than any other small P&S that I've used, but the lens barrel does not retract. Which means you've got a great, fast Leica lens and that's why you get better resolution, color saturation, etc. but it also means it doesn't really fit in your pocket.
The closest camera to the S100 is the Sony RX100, but again, you are getting only slightly better resolution while you are getting a heavier, bigger camera.
Another wonderful feature of the S100 is the ultra slow motion movies it can take. Yes, the resolution is low, but you do get truly super slo mo movies just like you see on TV shows.
Also, when using the regular movie mode, the image stabilization is phenomenal on this camera. You can literally walk around with the S100 taking movies and the IS will keep the frame so steady it actually comes close to giving the effect of using a professional Steadicam mount!
If you want a true pocket P&S camera that takes great videos and photos, you really can't do better than the S100.