Pros: High replay value
Great graphics
Excellent soundtrack
Overall top notch presentation and polish
Backstories for environments and enemies are very well written
Single player story had some surprising depth
Great "boss run" or "arena style" (Monster Hunter or PSO style) gameplay
Fights tend to not take very long - 20 minutes max with most fights being much shorter (sometimes literally just a couple of minutes)
Character cosmetic changes can be made at any time (and for "free") for face, hair, clothing, gender, and even name
Several methods of defeating bosses becomes apparent during the game as new spells/powers unlock, etc.
The game "feels" good - i.e. has polish, the movement/animations are great, sounds, music, visuals all combine together and accompany each other greatly. Awesome production values that feel like this was not just a "game made for a portable system". It is like Gravity Rush in that this feels like it could have come out on a "big brother" console like P3.
Definitely one of the "must have" games for the PS Vita.
Casting spells does not feel weak - seeing your character's animations during spell casting feels like you are a real powerhouse and not some wimpy "magic user" or wizard. The magic users in Soul Sacrifice are the supreme warriors in their world - and they look awesome when casting those spells.
Co-op and net code work great.

Cons: Character customization (clothing) is not much and most costumes have to be unlocked and there are not many options for cosmetic changes.
"Locked in" to specific costumes at highest levels if you go with the extreme "divine" or "magic" builds.
Not as many options for character build customizations (some people would find this to be a good thing though as it leads into the next con)
Not as much resource gathering as games like Monster Hunter (this again is a "pro" to some people but it means less overall complexity and customization to the game)
Sacrifice/saving mechanism is not quite as interesting in practice but is still fun
Divine character builds may have difficulty with completing certain optional quests that are required to be completed without taking damage or within a certain time limit. NOTE: I used a magic build so I am not positive of how a divine build would impact these quests so I think this may be a con but it might not be.
Equipment customization is not very present - your "equipment" is the spells you select before a fight and your arm "sigils" which are where you get certain passive boosts to stats, attacks, defense, heath, and to provide other passive powers.
There is a very good variety in spells, however, I wished that they could have provided just a tad more variety in certain areas (like summoning "pets" or AI monsters to help you, as an example).
People that join games online are sometimes not very nice due to the sacrifice/saving mechanisms but playing with friends is great.

Other Thoughts: Very awesome game and if you like pretty good character customization with an emphasis on being a cool spell caster then this is a must have game for the PS Vita.

I would ignore the stuff about this being "like" Mosnter Hunter. Yes, it is a game in same general genre but it is much faster paced and with less overall customization. It is not "as deep" as Monster Hunter in my opinion but that can be thought of as being good by some people. Basically, if you wanted to like Monster Hunter but just didn't like the resource gathering, didn't feel all that powerful, and don't like the fights lasting so long then you may enjoy Soul Sacrifice more. Try the demo from PSN!