I think Sony released the Vita prematurely, as the PSP was still dominating in Japan. And in the West, people didn't even really get into the PSP in the first place, so you can't expect much there for Vita. PSP already held its own in terms of graphical power, so there wasn't much need to release a MORE powerful handheld. I guess the two joysticks is a pretty big improvement but aside from that there isn't much of a reason for people to opt for the Vita over the PSP.