Finished Crown of the Ivory King, and the full DLC quest.
Well, technically I still have one optional boss to fight. It's located in what has to be the most obnoxious area in the whole game, and since the boss is just another rehash of a previous fight, I don't really care about it right now.
I loved the real boss fights in this DLC, though. The first boss is sort of like a guardian, not very difficult but (as expected) has something unique about it that'll make you scratch your head. In my case, I got lucky because I found the solution to the boss puzzle before I actually fought the boss. Needless to say, people are pretty mad about this one on the message boards.
The final boss is absolutely insane, but in a good way.
This fight has an interesting concept: you can recruit four other NPCs (plus the regular phantoms that appear before bosses!) to help you win the fight. The idea is that these knight NPCs will sacrifice themselves to seal the portals from which the boss's minions are summoned. Seal the portals and your reward is a (still tough) 1v1 fight. The problem is that the four knights are all locked somewhere on the icy land, and you need to do some hardcore exploration to find them all. But man, when you save them and go fight the Ivory King, it is such a great sight watching those 4, 5, 6 phantoms trade hits with the boss and his minions.
As for the DLC area, it was okay. Less complex than Iron King, still massive. I think I liked the Sunken City better, but maybe it's because I wasn't in such a hurry to finish that one. There were several parts of the snowy land that I just kinda rushed through, and I also used a guide to find one of the knight NPCs.
The "big surprise" that From was promising us for beating the DLC quest was very disappointing, to say the least. Bleh.
Still, it was a fun ride. I did the whole thing in NG++, so there was plenty that I didn't explore because I wanted to fight the bosses ASAP and see if I could beat them. I will take my time and explore these areas more carefully in some other opportunity.