I read this review...
http://uk.gamespot.com/features/one-month-with-the-playstation-vita-what-went-wrong-6349986/
pretty much bangs the nail on the head.
You bought a Playbook? Was it free in a free, promotional box of a new cereal?
Mobile gaming is never serious enough to warrant anything more than a phone or an iPod touch like device these days.
It will fail, because its another device to carry and the games wont compete with iOS/Android prices. (even if they are better, which they probably are)The rest of the market has been devoured by the DS.
Personally i don't know why Sony bothered wasting time on this.