I've had a S100 for month or two now and it's my most used camera, I also have a Fuji X10, 5DMKII (fully decked out including a trio of 600RT flashes), G12 and a Canon cheap P&S.
The S100 is always with me, actually gives a decent DOF, has a really good flash system, takes RAW, makes intuitive sense to a long time DSLR/SLR user, takes really good pictures, has GPS and has a simple menu system that is quick, intuitive and easy to use. I have a cheap Amazon Basics case and the camera is always on my belt, I'm constantly getting shots and little movie clips with it because its always with me, that I never got before. Every day I'm getting at least a few pictures because of this camera, whereas before it was mostly weekend warrior.
The 5DMKII with all of it's glass takes better pictures technically, but I also get more screw ups because there is so much more under my control. I use it far less too because it's big and bulky. Love it (the pictures) - hate it (the size).
The G12 is too big and complex for a small camera/P&S, and not good enough to qualify as a real camera. Sort of the worst of both worlds? I'm not interested in the G1X - better sensor but even bigger.
The Fuji X10 is a love hate. Neat camera - sucky firmware and I'm constantly missing focus. You have to go really slow and make sure you have your shot before taking it. Great panoramas though.
The S100 shots aren't anywhere as good when 100% cropped on my big monitor, but boy do I take a lot of pictures with that camera.