2nd Edition swaps a few things up: Now the focus is on the PC's making a difference, with a bit of a Gurren Lagannish "Do the impossible, Fight the power" theme to everything. The Yozi's are fleshed out more (Though they kinda screwed up by making them too malevolent in a setting where the general vibe of each faction tends to be mostly strong-willed jerks with a few outnumbered and outvoted decent guys), it really sucks to be an Abyssal now, Alchemicals have had a complete overhaul and Infernals are new.
As for Keychain of Creation: I prefer it to the actual setting. Keeps most of the cool stuff, but is more lighthearted, not so grimdark. When you've finished it, you can find the same author's currently running Exalted story Lunar Quest here.
Basically it's about an Amnesiac Lunar called Saulanna Rockblossom who's had a fragment of a Primordial experimentally grafted to her soul, and it's set after the Ebon Dragon has successfully escaped his prison and conquered the world.