That's when I got it too, I think. Might have been a mistake, since it was so early and I think it was a general 66% off everything.
I haven't actually used it though, yet. My opinions of the DLC:
Legacy of Rome: Retinues really streamline trivial wars, and adds some cool stuff like mending the christian schism or re-establishing the Roman Empire.
The Old Gods: Playing as a pagan is addicting, as raiding can produce a *lot* of dosh if you're a little careful. Particularly once you hit critical mass and can sack holdings instead of just robbing the fields. Scandinavia is just a fun arena, too, with the mobility of boats really helping. Reforming the religions is neat but keeping a tenuous gavelkind alliance of free pagans is kinda exciting. (Pagans can only use gavelkind unless they imitate the more centralized abrahamic religions).
The Republic: Eh. The opposing families are kinda cool, basically particularly dangerous vassals, but republics play slow and are a bit boring. Nobody wants to marry you, so you just end up upgrading everything until your income grows exponentially, then do whatever you want with allllll the mercenaries.
Rajas of India: India exists even if you don't have the DLC. It's just across the world from where I like to play!
Sword of Islam: Haven't tried it yet. I want to make an islamic trade republic at some point just so I can hold churches, castles, AND cities without penalty. Not sure where to start though.