This is my quick impression, comparing to my 10 minutes at the VITA kiosk in gamestop few weeks ago
1) The weight is really light!! - I didn't notice at gamestop, but it is really light. It was same surprise I got when I switched from PSP 1000 to 2000.
2) OLED is beautiful! - I didn't really notice it as much at gamestop, probably due to all the fingerprints and oils at the screen. But yea, when I actually saw it today, it was beautiful. I am iphone4 user, and I like VITA OLED's color more. But mayb because of ppi, iphone4 looks better on web browser
3) Build quality is great - I was a bit worried that it was all plastic, including the front screen. I still wish it had used gorilla glass, but it still looks and feel premium. I was actually impressed with the build quality of my friend's 3DS (compare to NDSL), but this is even better.
4) OS UI is better than what I expected from photos and videos, but it still has big room for improvement. I hope they will update it in the future, or allow more user customization.
5) d-pad, face buttons, and analog sticks feel great! I was worried about the button size at first, but it still feels nice. I think if I get used to it, it will feel better. L, R buttons are probably my biggest disappointment.
I don't know if its my wifi or vita, but PSN store download seems a bit slow.
Yea overall, it looks and feels impressive. The only thing I wish they would fix soon would be some UI adjustment and PC to Vita transfer.