Davelozzi said:
I know that the original poster didn't ask about Eberron, but since it's come up, I'd recommend against. The overall feel of AoW and the overall feel of Eberron just don't mesh that well, at least not from where I'm sitting.
Eberron works very well with Age of Worms. The entire setup with Katashka, the Wind Dukes, the Dark Six (Ebon Triad) cult, Age of Demons / Worms, Sharn, the Spire in Q'barra, the Principality of Redhand...it all works very well to create an epic story where the heroes truly feel like the weight of the world is on their shoulders.
For example, IMC Manzorian / Tenser is a dragon bound by the Prophecy. In Greyhawk why wouldn't Tenser join in the final battle? Or Elminster? Or the Harpers? Only in Eberron can you make a believable case that the party of adventurers are the only ones who can stop the Age of Worms. If it's really so terrible then where are all of the power players in the other settings?
The lack of gods is another major issue. Where are the other gods in Greyhawk and the Forgotten Realms when these events unfold? In Eberron Kyuss is a powerful fiend rajah, not some "demi" god. The AP is much more consistent in the world of Eberron.
As far as "feeling", I think this is more in how the DM runs the game, not how it's setup in a published module. There are many opportunities for intrigue and noir in the backdrops of Diamond Lake, Sharn and Alhaster. There are also a lot of over the top pulp encounters. The encounters are also generally very difficult, making it more suited to the somewhat more powerful options (like warforged and action points) available to Eberron players.