I got to hold and play a Vita for the first time today (one of my friends picked one up over the weekend). It's surprisingly light, and both the front and rear touch panels are more responsive that I was expecting. Just holding the thing fells soooo much better than a PSP. It made me want to buy one just to play PSP games with a second analogue stick and without cramping my hand.
I played a bit of Uncharted and WipEout 2048, and both were fantastic. The aiming in Uncharted was kinda wonky, but not much of a problem after getting used to it. I would like it to be improved though.
Overall, my little taste of the Vita makes me want one even more now. Which sucks, because I won't be able to afford it anytime soon, and I also have to get a 3DS for Fire Emblem and Paper Mario (and eventually Pokemon). My original intent was to pick up a 3DS sometime this year (probably get it for Christmas) and then get a Vita later down the line after a price drop/revision, but now I'm considering getting the Vita first...