First of all let me start with saying that i'm very excited about the PS4 overall. There is one thing that worries me though, and that's the choise of cpu. It's based on the AMD Jaguar architecture, wich is AMD's new architecture for low-power devices. Now low-power consumption probably sounds nice, but it also means it's much slower.
The Jaguar architecture is AMD's successor to it's Bobcat architecture. Bobcat was used in their E-350/E-450 APU's and is used in the cheapest netbooks and mini/htpc pc's. Moreover Jaguar is rumored to only be about 30% faster than Bobcat.
As a reference i have a mini HTPC with a e-350 and i can tell you, it's annoyingly slow and can only run HD videos properly because of the GPU video acceleration. Hounestly in games the integrated gpu can't even be fully used because it's so cpu limited. It's really more a cpu for internet/e-mail netbooks than a gaming console.