Regarding body size... I asked myself, how would it compare to a 35mm camera? So I took the liberty to combine some body pictures. Here is the result (equal scales!): http://aquarius999.x10.mx/dpr/CameraSizes.jpg
I was surprised! The analog P&S is a 'full frame' yet it's as compact as the Panasonic, and smaller (by approx 10mm WxH) than the G1X.
Should smaller sensor sizes (less than 1/2 of full frame) not translate into smaller cameras, at least from the standpoint of optics?
Finally finally... this is the G series camera we all were waiting for. The many versions (attempts to get it right) made one thing clear: there is no substitute for sensor inches.
Apart from IQ, the large sensor also allows far more control over DOF, as essential for true creative photography as control over shutter speed and aperture. I think most G series users (and others) are willing to accept the G1X size increase in return for DSLR-level quality.
Nikon with its V1 followed the 'mini interchangeable lens camera' trend but how many lenses will ever be changed? I think Canon did well by taking a direction that is more in line with the highly successful rangefinder cameras from the film age.