The games are expensive, agreed. But you are not comparing apples with apples. I love browsing on an iPad whilst watching the telly. But I wouldn't bother gaming on it when there is a PS3 in the same room. But with a PS Vita I get to stream games and interact with the PS3 without waiting for the kids to go to bed. Plus I get to use it when travelling in the car or when sitting at the mother in laws listening to mind numbing nonsense.
I don't like touch screens for the main controls, hence finally the long requested addition of the analogue sticks. The other front and rear touch screen/pad bring something new without forcing them on you as the main control. Pairing a controller wih an iPad to achieve the same makes it unportable IMO.
All in all, if I had the finances available it would have to be a day one purchase for me.