Soul Sacrifice and SS Delta

1. You keep up to 10 of all your essences and info on all your sigils, but sigil effects and requirements may have changed in Delta.

2. They're still great offerings, you just can't cast them as fast. Nothing has the targeting abilities they do, and there are even more of them now.

3. You not only keep ten of each essence, but also ten of each offering. This includes * offerings - so if you have spares past ten, boost them! You keep your allies, all at their rank, story progress (though you'll need to still go through Delta's intro to get access to everything again), raiments (except the ROA and Toukiden ones), and you get rumors based on what your level was, which is reset. Not to worry though, leveling is much easier now.

4. Given how save files on the Vita work, I would assume you need to have some form of SS on the system with the save on there when you make your new game in Delta.

Aside from the new bosses, offerings and maps, the vanilla bosses have altered and new attacks.
Maps have events such as certain paths becoming blocked, the ground splitting and dropping you into a different area etc. which can add a nice twist to the battle.

The customisation is expanded a fair amount with the unlockable accessories and raiment mix-and-match feature. One thing that disappointed me is the white, black and gold colours aren’t as special any more. You don’t obtain them by defeating x amount of archfiends, but simply buy them from the Bazaar. The gold colour also looks worse than in SS.

Alice’s Maze can last hours depending on how far you want to go, and rewards you with titles, clothing and points for your faction, which you use in the faction leaderboards to try win items weekly depending on your position and where your faction places.

Rumours add bonuses when equipped, such as weaken fiends/archfiends, gain more EXP etc. whicch makes levelling to 100 over and over easy.
Once you max out your levels you can transmute, which gives you the choice of a Heart Sigil. For example, if you use weapon magic a lot, you can choose the corresponding heart sigil, which will give you +100% weapon attack when equipped. There are constraints, though, as each faction is limited to what heart sigil they can choose (e.g. Avalon can choose the arm heart sigil, but if you’re in Grim or Sanctuarium you can’t.)
Every time you transmute, you can choose the same sigil again to boost it by 5% each time, or choose a different sigil for a different offering type. You can transmute up to 99 times and each heart sigil has ten levels.

This ended up being a much longer post than I expected, but I hope I didn’t ramble too much.