Got mine last month when Best Buy gave me a $60 gift card for purchasing one.
I guess most of them have OLED problems. Mine is kind of streaky and has blotches that show up on black screens. Reading online, I figure that just getting another one won't really help, so what I did was buy the two-year extended protection plan with accidental on PSN and I'll exchange it in three years when the tech is smoothed out a bit.
I absolutely adore Gravity Rush. If you have a Vita and have not yet gotten Gravity Rush, you are doing yourself a great disservice. I actually got my first platinum PSN trophy tonight for 100%ing it, that's how much I love it.