You are correct, it is based off of the powerPC. Also, there is not really any comparison for the GPU because of the proprietary technology in it (it goes beyond just unified shader and 48 pipes, it also has special cache access, procedural synthesis, and many other new concepts). Thing is, this is the first title that is just starting to show the realization of the hardware capabilities. People mistakingly think its mostly hardware that determines, but its also in how the programmer utilizes instruction sets and learns more of its hardware and instructions. This takes awhile though, as with any new hardware. Takes awhile to use its potential.
If you argue with an idiot he will drag you down to his level and beat you with experience.
I am not a fast writer.
I am not a slow writer.
I am a half-fast writer.