3rd edition of Nobilis doesn't change any of the fundamentals of the game, but rearranges the whole very nicely -- which is not to say that there aren't any mechanical or setting changes, just that core of the game remains intact.
* Descriptions of Heaven, Hell, Light, and Dark have been adjusted. They aren't incompatible with the old ones, but reflect a different side -- a more playable and more interesting side, I think.
* Persona and Treasure replace Spirit and Realm. This is an excellent change. Spirit and Real were always a bit bland, whereas Persona and Treasure are full of flavour.
* I absolutely adore new Bonds and Afflictions, and Chancel and Estate Properties, and the way they work with the rest of the mechanics. This is the way it should always have been. Want your character to "always win"? Can do. Want your character to "be known by name to everyone he meets". Can do. Great, great stuff.
* Destiny and Projects system replaces character advancement rules, and also provides a robust seeming way to handle proper Noble projects like "free all souls from Hell". This rocks.
* Mechanics for Mortal actions and Imperial Miracles -- a substantive improvement over the old "mortals don't really matter, and Imperators are hand-waved". (Imperial Miracles aren't completely out of PC reach, either.)
* I like that it is written for players more than HGs. I like that it makes the game approachable. The majesty still lurks in the flores, but the main text is more driven by energy! and whimsy. You get the feeling "WOW! I MUST PLAY THIS AT ONCE!" not the "Oh, awasome. I must think about this and then I may be worthy of running a humble game. Maybe"
* Some of the art is great, some I don't like at all. Tastes will wary. Some of the things I didn't like at first are growing on me, though.
* Zu. I like the concept, but a tiny bit more detail would have been nice. ProTip: http://imago.hitherby.com/?attachment_id=3089
* Minimal number of examples makes the book quick and easy to read, but a
few more things could have used an example, but none of these things are show-stoppers. Maybe we'll get a webified FAQ down the road.
What I didn't like or missed:
* No Chancel Properties for Locust Court. Dionyl left out almost completely.
* Imperator creation could have used more detail.
Overall, I give it 9 points out of 10 -- or 5 stars in this case.