I've somewhat mixed feelings about Eberron, but I expect I'll pick it up, and as I'm trying right now to decide what setting to use for a game I'll be DMing, I may use it.
On the one hand, I've been feeling like I want to play in a much more primitive world for a while--where people are really scrounging for a living.
But on the other hand, I've been feeling like I want the PCs to really really be movers and shakers.
And knowing that I have people who want to play a variety of races, a more metropolitan world seems like it might be better. I've just been reading through my Kalamar stuff, among other things, and while the racial tensions are interesting, the fact that only one or two cities in the whole setting are very mixed in terms of races is rather off-putting.
So I suppose I'll see how things go. I might just do a custom-built job, but if I'm still having a hard time deciding when Eberron hits the street, it's not unlikely that I'll pick it up and start using it. Having a setting in which there are groups of all the various races with very distinct cultures, but in which there are other cultures in which the races mix well appeals to me. It "clicks" for me in a way that the standard treatment of "dwarves live in the mountains, elves live in the forests, humans live everywhere else, and only Yondalla knows where the halflings and gnomes manage to eke out a living" just doesn't.
It also seems designed (for all the frequency of low level magic) like a world which is designed for PCs who are the real movers and shakers of the place. The highest level friendly NPC cleric is level 16, yet there are bad guys who've been manipulating things from behind the scenes for many many centuries.
Anyway, we'll see how things go. It's nice to have a large setting so you can see the wider picture, especially when you're looking to start a new campaign from scratch already. And it's also nice to have something different, but not seriously changing the core rules. I *could* run something like Midnight, or a custom campaign built around TEoM, or whatever, but I've been having more doubts about that as time goes on--mainly because I don't want to force all of my players to spend a long time absorbing a big chunk of new material at once. With Eberron, it seems like I'll be able to combine some details about the setting and the various cultures fairly quickly--which will introduce the biggest things that *are* different without having to pass out photocopies of large chunks of books.
Edit: Oh, and I left half-orcs out of my standard treatment above. Which, considering that one of my players definitely intends to play a half-orc, is rather telling. ^_^;;;