Eberron has a ton of very clever ideas that I really like (and will happily steal and put into my Greyhawk campaigns). They really went out and came up with new ideas, breaking from the Tolkien/Earth history tradition, and I think that's to be lauded. I feel though, to a certain extent, it's a patchwork of good ideas, but it's a newer campaign setting. As campaigns are played and "support" materials are published (novels, sourcebooks), it'll develop into a full, well-integrated world.
I have no problem with Eberron's "theme" -- either you like it or you don't. I happen not to run the setting, and the other players in my group prefer Forgotten Realms or Greyhawk, but I certainly don't mind if someone does like it, and I'd happily play it.
The only issue I have is with the campaign world itself. For some reason it reminds me of an MMORPG world. Like, "here's the forest zone", and "here's the swamp zone", and "here's the desert zone with feral halflings", and "here's the jungle zone with lizardmen", &c. The Mournlands and Demon Wastes are the "mid level" zones, and then Xen'Drik is the "high level" zone. Argonessen is the mystery land that your clan might be able to explore when the developers put out the expansion pack to let you level to 70. Ever since I looked at the map and thought "World of Warcraft", I couldn't get the "MMORPG model" out of my head whenver I attempt to interpret the world itself. Of course, it doesn't really matter that it's like that -- in fact it allows for integration of all the cool ideas that the developers came up with -- but it just doesn't appeal to me.
In the interests of full disclosure, I love Greyhawk -- primarily because it completely rips off European history and the Tolkien tradition. Being completely honest (not snarky at all), I guess it's easier for me to get into a game if I can relate it to something with which I'm familiar and I don't have to use my imagination quite as much. Or maybe in a different way. But given that I have such a negative "Reviewer's Tilt" and still like what they did in Eberron, I guess that's pretty good.
I'm Cleo!