From what I understand, the MGS4 demo was a straight port to PSP2 code, no optimizations or lower-res assets. I'd say that's pretty good.

As for the PSP2, I wonder who the market is for this. I portable PS3 is a cool, but I'd rather just play home console games on a home console, with an HDTV and all of the buttons. The DS/3DS at least allows for unique experiences, what with the dual screens and stylus. Android phones and iPhones are now competitors in the portable space, too.