Got my vita yesterday. I'm impressed with the system. The only full game I have so far is Motorstorm RC, but I tried a couple of demos. Rayman in particular blew me away. Will pick it up when it comes down in price, considering it's 29.99 on practically every other system. Graphically Wipeout 2048 looked amazing with near flawless image quality. The OLED screen really helps.
Regarding the blotches; yes, I did see them but only when I had the lights off with the screen brightness set to the minimum. This was mainly only visible with a completely or near black screen. I did notice them a little when using netflix with some darker shows, even when there was "stuff" on the screen. So I guess beware if you plan on using it for a lot of movies with your lights off. Otherwise, nothing to worry about. Besides the blotches I didn't notice any other screen anomalies.
Basically I was worried I'd regret my purchase but ended up surprised by its quality. It really felt like playing on the perfect handheld. As long as this gets properly supported by publishers/developers I'm a happy camper. In the worst case scenario, at least there are a lot of PSP games out there that I can enjoy.
Thumbs up.