This is definatly the most enjoyable DLC I have played for CK2, although there is room for improvement. The Satanist cult is definatly the most ineractive and enjoyable to play, the other societies, not as much. The Hemetic Society is possibly the second best option, but really needs more interaction on par with the Satanists.

Did I have fun playing as a satanist? Yes, it's a lot of fun and some of the options do make things easier with minimal repercusions. Factions can easily be stopped just by possesing someone, but what makes it so much fun for me is the variety of things you can do, the other societies don't seem to offer that.

Vassalisation can be a bit rediculus but you do have to convert those rulers into satanists first, I've not seen what happens once you die with such a large empire, I can't imagin it being all that stable! Unless your heir is the spawn of Satan, in which case, instant ruler of the cult again!

Overall, I think the other societies need fleshing out a bit more to make them as interactive.