Old Gods is out and is pretty much what it said on the box. Can't comment on if it was worth the 15 before I've played 40 more hours of it, but it feels pretty solid.
Christianity is already divided in two in the game, which I guess might actually be correct if they want specifically Orthodox Christianity to be able to spread into the Balkans and Russia, but it's probably not the right term for it? The expansion may not be deep enough for them to have been able to take that into account.
Religion now gives you abilities as a character which is pretty cool. Norse pagans get to conquer all sea-connected territories without reason. The Norse abilities feel pretty "game"-y, so to speak, but the rest of the religions have pretty though through ones like being able to get a divorce from the Pope as a Catholic and have several wives as a Muslim. These were already things in the game but a list of it is not presented to you if you hover over the religion icon in someone's character page.
Haven't really grasped raids and loot yet. Apparently a condition is that you're in friendly lands?