Hmm.. $600 sounds a lot indeed with all the mirrorless madness going around. But compared to the predecessor;
A jump to a larger and CMOS sensor sounds promising since it will be driven by a DIGIC V. Good formula for less noise.
One stop faster lens (on widest), maybe a 24-156mm (just speculating with the 6.5x) would be a welcome upgrade. 24mm on this larger sensor would be a lot wider than the 28mm of the current G12.
Better video, better screen and probably lots more little ergonomic tweaks...
... could make this Powershot well worth the $600 for people who want neither a DSLR nor a small compact but a small, light, complete solution with great IQ without the need of changing lenses