SecondTime said:
The supplements, because they are intended to provide more detailed plot hooks and a smaller level focus on the setting, tend to emphasize the more traditional DnD themes, i.e. feudalism, adventuring, etc.
The bolded part, for some reason, made me think of the thumbnail sketch of each of the Five Nations in relation to the standard D&D party: Karrnath = Fighter, Aundair = Wizard, Thrane = Cleric, Breland = an Expert or Artificer subbed in for the Rogue, and Cyre, having been destroyed, as that most maligned fifth wheel, the Bard.
I haven't been able to put my finger on a distinct difference in flavor between the ECS and the supplements that goes any farther than the difference that will arise any time you have different people writing about the same topic. In some ways, I think it boils down to fanboyism run a bit too rampant (stating for the record that I am a frothing at the mouth fanboy myself); I think that Hellcow (and James Wyatt, whose contributions to the ECS go unsung all too often) did an amazing job with the initial setting, and the support he's provided for it after the fact has been nothing short of stellar. When there are disagreements about specifics, I tend give a bit more weight to Hellcow's opinions about it than those of others, but I try to remind myself that the setting, while his baby, has grown a bit beyond him now, and I have to allow for the input of other contributors.
The only real beefs that I've been able to identify in the supplements so far are some of the sidebar information in the PGtE, particularly about the inclusion of subraces (IIRC, the setting has absolutely *no* need for them), some of the PrCs in Magic of Eberron (they all seemed a bit too heavy on the transformative side of things without any real solid reason for them - "this class will let you eventually become... <rolls dice> undead! wait, no, an aberration!"), and the fluff text in some of the chapters of Races of Eberron. In all of these cases, though, the information is easily ignorable or replaceable, and very very minor in the grand scheme of things. IMO, the only real contradictions that the supplements could make would be metaplot advancements, revealing bits of information that by canon are up to the DM (the true cause of the Day of Mourning, the powers of the Mark of Death, etc.), or complete reversals/mischaracterizations of previously published NPCs ("the Quori aren't living embodiments of nightmares that want to halt the turning of the age out of self-preservation, they're beings of pure light who want to give children candy!") . I don't worry too much about things like that happening.