So we've talked about what's familiar, now some notes about what's distinctive
Rounser, if your rush to disagree with everything I'm saying, you're missing my point. I'm
not saying that the more distinctive aspects of Eberron are there for you to ignore. Whether you're talking about the Lightning Rail or the impossibly tall buildings in Sharn, applied magic is a part of the setting that you're definitely going to run into when you're in "civilized" areas. Similarly, as I said above, psionic abilities are an integrated part of the setting (though a bit easier to ignore, since Sarlona's not exactly welcoming).
My point is not that you can strip all that stuff away if you want ...because if you do, you might as well just be playing in Greyhawk. My point is that the seemingly disparate elements of the setting are so well integrated with one another that most folks playing in Eberron won't want to ignore them. For example, I normally wouldn't play with psionics in a D&D game, but I really like the way psionic abilities are tied to the history and cosmology of Eberron.
A campaign setting trying to be as diverse as the "real world" without this background knowledge is bound to look incoherent.
Well, isn't that what sourcebooks are for? WotC is hoping to fill several books with background knowledge. It's in their best interest to create a setting that takes a lot of books to fully explain.
If you're looking for a common thread to tie everything together, though, look to the planes. While on its surface, Eberron is a pretty classic D&D world, you'll find a lot of outsiders and extraplanar phenomena if you dig a little deeper. Couatls and rakshasas battled each other at the dawn of time, sparking a conflict that persists in some form today. Druids exist not just to revere nature, but to defend the planet against the outsiders that invade when other planes are coterminous. Psionics tap into the power a plane where dreams and nightmares are entirely real. Aberrations are the result of an ancient alignment between Eberron and the distant plane of madness, an event that will be repeated soon. Lycanthropes were hunted nearly to extinction, but thrive in a sylvan plane. Demons who came to Eberron centuries ago are trapped beneath the earth itself, marhsalling subterranean allies while plotting their escape to the world above...
Add to that the biggest unknown: Dragons. They're there and they're very significant. They're prohpecying
something, they're somehow associated with "dragonshards" and "dragonmarks," and they're on Eberron's side against all that extraplanar nastiness.
So yeah, don't worry about coherence and backstory. Eberron will have books full of it.