After trying the game I must say I am disappointed. The atmosphere is good yes, but the game looks limited. I don't like this Monster Hunter kind of controls, I just find it is slow and dumb, and I hate having to use the left shoulder button. Not buying for now.
I might try Soul Sacrifice later when it's on a discount, but it really looks like a game built almost only with multiplayer in mind. I definitely recognize traces of Inafune's Lost Planet design in this, and I wasn't really fond of Lost Planet.
Also I tried the Ragnarok action RPG, now this one is total garbage, don't play this.
While I can feel this limitation in some places, I'm far from dissapointed. The only limitation we have is the game being based on small battle arenas. There is zero exploration, there are no maps to discover, you are just dropped into a small to medium sized place, and FIGHT. But everything else is fantastic IMO. There are lots and lots of spells (the whole combat system is based on spells), you can upgrade them, fuse them (making new spells). Character development is limited in a sense that you don't gain XP, but you improve your defense, health or attack, by deciding whether you save or sacrafice your enemies. You gather different sigils, which can be used to customize your right hand, and through that, your attributes. The coop battles are easy to jump into, they are like boss battles of Dark Shouls. Funny that you can also save or sacrifice your allies in battles. Saving means that you heal them, sacrificing them means you unleash some badass spell.
The game is also challenging in places, not Dark Souls level of challange, but it is not a cake walk.
The graphics are not amazing, not even for a Vita game, because I've seen sharper, more detailed games, but the art design is very good. This is accompanied by an amazing sound design and an interesting story about a sorcerer, who lives in a twisted world, where sorcerers are monster hunters. S/he looses someone close to him, which causes him slowly falling into madness.
I tried the demo for Gravity Rush too, and this one looks far more interesting.
That's an exceptionally good game, have fun with it.