My comment was meant in general, not specifically directed at NLKS because WagnaPaiva said that "back in the day..." the standards were different :P

I haven´t  played it on the Vita tbh, but when it is half as good as the Wii version, I´d recommend it too

Stealth Inc., Pixel Junk Monster HD, Flower and Sorcery Saga all come to mind and I do not remember seeing them listed already.

Let's see:
Tearaway
Killzone Mercenary
Wipeout 2048
Plants vs Zombies
PixelJunk Monsters Ultimate HD
Dokuro
SoulSacrifice (or wait for Delta)
Gravity Rush

Mortal Kombat and Injustice are great on the Vita. Tons of content that, if you're a fighting game fan you'll be playing forever. Spelunky is also a personal favorite and dirt cheap. I think 6 bucks or less.

<_< I would strongly recommend not getting Soul Sacrafice. I got it for free on PS Plus and really didn't care for it at all.

I recommend a 32gb memory card (go higher if you can a 64gb will have you set).
Gravity rush
Uncharted
Tearaway (A hidden gem in my opinion. Also a very underrated game at that)
KillZone
Guacamalee (i was very surpised by this game in a very good way. Its very similar to metroid minus the guns and blasters)
Little big planet
Soul Sacrafice
Toukiden
There are some good indie ones too.

Besides all recomendations, get PS+ and a 32GB or 64GB card. Right now, the following games are free:
- Uncharted Golden Abyss
- Gravity Rush
- Street Fighter X Tekken (highly recommended)
- Wipeout 2048
- Modnation Racers: Road Trip

And with Monster Hunter and Unit 13 latter this month. I have PS+ since November and I got Rayman Origins, Souls Sacrifice, OddWorlds: Stranger's Wrath, Sonic All-Stars and other for free too. You could pretty much buy a Vita, a bigger card, no other game and just play Plus offerings and would still have a lot of games to play. And for what I'm seeing, you have a PS3 too, so it would be a pretty good deal since you would get at least 4 or 5 games monthly.

Street Fighter X Tekken is also free for PS plus.

Velocity Ultra is probably the funnest game I've played on the Vita and perhaps the only game that's better on Vita than on PS3 (imo). Best of all its only $2 with ps plus. (or at least it was last week)

Ys: Memories of Celceta.

I'll second Dokuro. An immensely charming little game.