I have to admit that, although i enjoyed reading the entries, at first, i wasn't overly impressed with the Age of Worms. Part of it was a bit of apprehension about Kyuss himself, as his spawn were never my favorite undead creatures. But i've enjoyed them, and i sat down and reread all of them (so far) back to back, and when viewed as a whole, i have to admit that i like the Age of Worms a lot. I think it's a fantastic campaign, and i look forward to dming it in the near future. hell, i wouldn't mind playing it, though that's always a challenge, trying to play a campaign that i've read objectively.
Paizo has, in my opinion, matched and exceeded the Shackled City, no small feat. Cauldron has a sense of single setting feeling that the Age of Worms doesn't quite, but the Age of Worms has a chance for the players to grow as individuals against one amazing backdrop and a feeling of being involved in something truly epic.
I just found out about The Shackled City recently from some folks over on the Monte Cook's Iron Heroes messageboard. I got both the Shackled City and the Dragon Compendium and I'm very impressed with both.
If Age of Worms is as good or better than the Shackled City, I will buy it if and when it's made into a hardback package like the Shackled City. I really hope there are plans for this to happen!