Canon g15 vs g9

Long time owner of the powershot g9 loved that camera took great pictures and had tons of options. Never upgraded to g12 g1x or any model after that but Wanted to know how does the g15 stack up against the g9 in terms of size comparison , options, resolution, mainly size of camera. I live in Az and its impossibly to find g15 in stock to take a peak  but how does this camera compare to the g9. Anyone former g9 owners want to chime in,  ready to step up to g15  but want to hear from you guys, thanks