Eberron is more steampunk, magic is uesd like technology is today.
Um, "magic is used like technology is today" != steampunk. And it's also not an accurate way to describe Eberron. I think it's fairer to say that Eberron is more Renaissance-era high fantasy, where your typical D&D settings are medieval-era.
One of the design concepts was that low-level magic (I think the rule of thumb is, 2nd-level or lower spells or effects) is commonly available, either due to native spellcasting abilities or because of magical items. The dragonmarks are related to this: a significant segment of the population can generate very specific low-level effects from their dragonmark. The catch is that these "dragonmarked families" have worked very hard to use those dragonmarked abilities to either completely dominate a segment of the economy (Cannaith and artifice, Jorasco and healing) or invent new and unique trades (Vadalis offering magically-enhanced or "magebred" animals and mounts, Sivis making quick long-distance communication practical).
Many things in Eberron are intentionally different from "the way things ought to be" in traditional D&D. A cleric doesn't have to match their deities' alignment in order to receive spells, and Eberron is the first setting to step back from dragons being "color-coded for convenience". Darguun is a nation of goblinoids, kobolds can be seen roaming the streets of Sharn, and the lands of Droaam are ruled by medusae, minotaurs, and night hags. The giants of Eberron ruled a massive empire in Xen'drik in ages gone by.
Wizards is (so far) also trying to leave Eberron up to the individual DMs to flesh out; certain campaign elements have been intentionally left up in the air, such as "what caused the Day of Mourning that destroyed the nation of Cyre?" and "Who is the Lord of Blades?" Xen'drik is an entire
continent that will never be thoroughly described, and there's even an in-game rationalization (the Traveller's Curse) as to why specific directions to a locale in one source or campaign may contradict directions in another source or campaign.
Wizards was trying to push a "noir mentality" in doing Eberron adventures, where the many and varied factions and conspiracies could be used to provide memorable twists (trusted NPCs may have a hidden agenda, shifting circumstances means that you may find yourself allied with the Blood of Vol cultists who were trying to kill you a few weeks ago, etc.). I don't think that's survived, especially in the few published adventures they've released, but the Inquisitives and Lanternlight Files lines of novels provide some good fodder. Oh yeah; novels are non-canonical unless otherwise referred to in source material (this has happened once that I can think of), which is one of the things that I grew to dislike about Forgotten Realms -- not because Wizards said the books were canonical, but many of the FR fans I've encountered treat them as if they were carved on stone tablets.
Eberron has a civilization which is heavily steeped in psionics -- the people of Riedra on the continent of Sarlona -- which is the most intriguing presentation of psionics I've seen in a D&D world; most others either ignore it outright or relegate to a minor section of the campaign setting (Dark Sun being a notable exception, IIRC). Every time I pull out the
Secrets of Sarlona sourcebook, I itch to play a kalashtar monk stalking the mountains of Adar...
I didn't have a problem with 3.5e Warforged, but I also think I like the design changes in translating them to 4e; it should go a long way towards refuting the "they're just robots!" mindset people had.
As for the rest of the 3.5e -> 4e conversion, I'm excited to see what they have planned; they surprised me with the Warforged, I'm hoping they do so again with Artificers.
