i really enjoyed
bentleys hack pack
you get dozens of levels of shoot'em'up ,twin stick shooter and sensor(six axxis)controlled stuff
for 3euro

strangers wrath is a great looking port

and jet set radios style looks really awesome on the oled screen(the only problem:i never figured out to jump in a proper way.neither on xbox real 1 nor on vita.therefore no real advice)

Seconded. Just started my 2nd playthrough.

My list would be:

1. Persona 4: Golden
2. Uncharted: Golden Abyss
3. Jet Set Radio
4. LittleBigPlanet Vita

...I need to buy more games.

Assassins Creed Liberations?

Personally, I would put Gravity Rush as the number 2 game; only because Persona 4 Golden is absolutely amazing. But Gravity Rush was just in a league of it's own, and showed how much potential the Vita has, in both hardware and overall game quality. Easily my personal favorite on Vita, and one o my favorite games overall.

I bought a copy of Soul Sacrifice on launch day, and still have yet to play. Any good?

It's great if you can get past how repetitive it is. You'll either find it addicting or boring, I personally find it addicting.

No Mutant Blobs? I am against this list.

NfS MW does not belong imho. The game is severly gimped on Vita and the sub native resolution forces you to learn every race inside out because 300m in front of you there is only a wall of pixels. I personally didn't enjoy it at all.