Just a few things that I've noticed from playing the system and some games a little for a few days now:
PSP backward compatible stuff looks swell. Tekken 6 character portraits are a bit muddy, but once the action starts, this thing is beautiful. Controls great, too. Really glad the D-pad works so much better than the original PSP's old crappy d-pad, or the 3DS' awful pad (Hated my brief time with Tekken on 3DS).
As I tweeted, "Uncharted for PS Vita is a reminder of how much hand-holding modern-day AAA games do. I barely feel like I'm playing it." At this point, the Uncharted story and gameplay are getting pretty formulaic, and the Vita version looks great and controls impressively. But really, there's nothing novel here. It's like a new Call of Duty game, competent craftsmanship without the heart or creative inspiration that makes a game special.
Little Deviants is neat, but would be better if they mixed up the minigame action more. I've only played through the first couple "levels." I would have done more, but when each "level" consisted of making me play increasingly harder versions of the game mini-game 7 times in a row, I lost interest quickly. A minigame collection should never be tedious. It just shouldn't be.
Touch My Katamari is a joy to play so far. I love the storyline and it's winking acknowledgement that the series went to crap for a few while there. I haven't enjoyed a Katamari game since the original, but this one is my favorite Vita game so far. The sense of humor is perfect, and the gameplay tweaks (squishing the Katamari to be tall and skinny or short and fat) are fun to toy with.
I've also tried (ever so briefly) Rayman Origins and Ultimate Marvel vs. Capcom 3. The former is gorgeous. The latter controls much better than I expected without a joystick. I suspect I'll buy them both sooner or later.
The built-in AR card games are neat (fireworks), eh (cliff diving), and confusing (table soccer). AR stuff could be impressive, but I really want to see a game where the cards have a deeper impact on gameplay. For instance, a tower defense game where your strategic placement of turret cards would actually be crucial to success. Also, my girlfriend is completely smitten with AR stuff, and can't wait to see more. I'm thinking there's an opportunity here for Sony to court more casual audiences, hopefully with more enthusiasm than Nintendo's 3DS AR stuff has been conducted.
The abundance of programs on the dashboard that require an Internet connection really make the system feel crippled when you're not near a Wi-Fi point or on 3G. I don't think this is a good thing for Sony, because I doubt the 3G adoption will be significant until people have better reasons to sign up. Instead, people will just feel like their brand new systems are hobbled out of the box.
Anyway, early impressions of the system are very positive. I don't regret preordering one in the least, and if Sony ever brings the memory card prices down, I look forward to ordering a ton of games off the PSN.