Let's put it this way........is the DLC worth it?
I've picked it all up, but not used some of it (Polynesia, Spain, Inca, maps), mostly for the added diversity of AI civs it adds. Thoughts on the ones I have used:
Denmark: Haven't played as this civ in the main game, but I do like playing with Harald as an AI. The scenario is great, and I like the Berserker as well as the Danish UA.
Babylon: General sense that this is currently the game's most powerful civ, mainly because it's tailored to the sort of quick science victory that's popular with 'Win on Deity' types. It makes a bad AI civ mechanically because the AI makes no real use of Great People and the strategy required to use them well has too many moving parts for it to handle. I've played as Babylon but don't find doing so interesting. No scenario, which is a shame.
Korea: Also a civ I played once. More flexible and more to my taste than Babylon, while still science-focused. Sometimes does well as an AI, usually dependable diplomatically. Haven't played the scenario.
Wonders of the Ancient World: I play with a friend in MP who doesn't have DLC, and for me the Mausoleum of Helicarnassus (and to a lesser extent the Temple of Artemis) are now so much a part of the early game that I'm always disconcerted when I can't build them. This is a cheap DLC but I'd say worth it - the new Wonders are interesting designs that support different strategies; two are valuable early game and, while I've tended to neglect the Statue of Zeus, I tend to find I regret not having it if I play aggressively - the AI likes to prioritise this one. Played the scenario, which has an interesting 'reward' system (different styles of play unlock different Wonders more quickly), but I didn't find it as engaging as the 1066 one or that it gave me much incentive to replay it.
As for the others, Isabella as an AI is another usually dependable diplomatic partner. So is Patchacuti, as long as you depend on him to declare war at the first opportunity. I haven't so far formed much of an impression on either of their personalities. Kamenaha I find more interesting to play against.