Ive used it about 4 times so far now. I definitely save it as a last resort as it is meant to be. You don't want to have to go through a battle with the side effects (half Def, blurred vision, etc). As long as You save it as a Finisher, and you have ample Lacrima, there isn't much consequence. I finished the Archfiends off with it, then after battle just undo the negative effects with Lacrima.

What I am currently doing is getting the hang of Destroying Cursed Body Parts. Usually its the Head/Wings of an enemy. Doing so gets you bonus items that don't normally show up. 

Whats the Most Bonuses you have achieved? 

I've gotten to around 500 or so with Sacrifice(x3), Counter(x3), First Strike, Minds Eye, Destroy Cursed Parts (x3),Reward Bonus Sigil, Godspeed Quest, Vunerability, Skillful Attack, Nearly Unscathed, Black Rites.

Yeah I typically use it as a finisher too not because I need it but because it saves a few minutes of battle time. As far as bonuses I think the highest I've gotten is 450 but I don't remember what all I did. 

come on guys ive broken 600 multiple times. although i normally score lowly because i run a heal and blood canon set up. what level are you guys? im 40&15 devine arm 4

Just beat Magusar at level 42 and 15, found it somewhat difficult but that was my own fault for taking bad spells with poor sigils to compliment them. Now time to beat the Avalon pacts and platinum the game. Definitely my favorite Vita game, Persona 4 being a close 2nd

I used them at first a couple of times... but each time requires more lacrimas to renew... so I stopped and began to look for archfiends weakness... and since then i have used it only once...

The easiest way to defeat the archfiends is to find their weaknest... the cerberus was a piece of cake twice in a row on the single player once I ajusted the sigils, magics and let magusar die... fighting solo is way better... :)

I'M SORRY! I JUST WANTED TO SEE THE ENDING! D:

XD

Seriously, though. I'm trying to get better gear so I can fight him without it--but I'm actually having a much harder time with the later Avalon pacts than I did with Magusar BEFORE using the sigil. :p

I'm level 18/26 dark arm 2 right now and I could probably get 600 if I went for godspeed, cursed parts, and unscathed during some fights but I always end up getting either impatient and nearly get myself killed or I spend too much time killing smaller enemys lol. 

http://www.vg247.com/2013/05/07/soul-sacrifice-3-free-dlc-packs-detailed-for-western-release/

Soul Sacrifice: 3 free DLC packs detailed for Western release

Soul Sacrifice developer Comcept is giving away a string of free DLC for its PS Vita romp, alongside paid content. Details of the first three packs have been spotted in a GameStop store and have been posted online for all to see.

CinemaBlend has detailed the free DLC slate based on what it saw in GameStop, and it goes as follows:

May 28 will see the ‘Headless Knights and Starving Ruin Dwellers’ pack added to PSN. It adds new bosses Dullahan and Behemoth into the mix, as well as a Goliath map, Berserker magic, eight new missions, and augmented reality support.

June 11 sees the release of the ‘A Drunk and a Chef’ pack, which will add new bosses Dwarf and Ogre into the mix, along with eight additional missions.

Finally, June 25 will see the Wild Wheels and Apparition pack added on PSN, which includes new bosses Ouroboros and Wraith, another eight missions and Angelus magic.

These all seem fairly generous indeed. What do you think? Also, be sure to check out our Soul Sacrifice appraisal if you’re on the fence about it.

So its better to sacrifice than to save?

Pretty much. The offering restoration is FAR more useful in combat than the life restore that comes with saving. Plus you get more points for the mission from sacrificing. They were clearly stacking the deck against going the divine route as far as upgrades go.