Chapter Two: Character ClassesThere is one new base class in this chapter - the Artificer, a character good at building and taking things apart -- specifically magic items. The rest of this chapter is devoted to defining changes to the core classes, as well as giving an NPC for each class. The changes to the classes are interesting, where they are present. The Cleric, for example, no longer has to be anywhere near the same alignment as his diety - allowing for more intriguing games where the Cleric of some good god isn't necessary good himself.
The NPC entries are a waste of space. I can't really see how these were really a necessary inclusion. If I want NPCs, I'll buy a book where I'd expect to find them, such as a city sourcebook (like Sharn: City of Towers - an Eberron sourcebook).
Chapter Three: Heroic CharacteristicsAction points start this chapter out. This is an idea that's been houseruled into many games so far, and it's nice to see Wizards of the Coast finally get on the ball and introduce the idea into one of their settings (barring the fact that they were also in Unearthed Arcana 3rd Edition). Action points allow characters to accomplish tasks usually out of their reach - a neccessity for heroism. A few new rules for skills follow, then onto new feats.
There are quite a few new feats. Just to whet your appetite, I'll name off a few: Aberrant Dragonmark, Child of Winter, Dragon Rage, Extend Rage, Flensing Strike, Heroic Spirit, Improved Damage Reduction, Knight Training, Music of Making, Powerful Charge, Right of Counsel, Urban Tracking, Whirling Steel Strike.
After feats, a full treatment is given to Dragonmarks -- magical tattoos that manifest on members of certain Houses, and grant different abilities and rights.
The chapter rounds out by listing and detailing the various religions found in Eberron.
Chapter Four: Prestige ClassesEight new prestige classes are presented in this chapter: Dragonmark Heir, Eldeen Ranger, Exorcist of the Silver Flame, Extreme Explorer, Heir of Siberys, Master Inquisitive, Warforged Juggernaut, Weretouched Master.
Generally I don't like prestige classes, and I feel that if they're to exist -- then they must add something necessary to the game. With that in mind, the Dragonmark Heir is interesting, but I don't feel entirely necessary. The Eldeen Ranger is also interesting and useful, but may have been better served being replaced with some extra feats available to normal rangers, rather than as a new class. The Exorcist of the Silver Flame functions rather well for its intended theme, and seems fun to play if you started out as a paladin.
The Extreme Explorer, Heir of Siberys, and Master Inquisitive are all 5 levels or less, and seem to be rather useless and/or unnecessary.
The Warforged Juggernaut and Weretouched Master are pretty cool prestige classes designed for their respective races to become stronger and more in touch with their ancestry. These are the two I'm most fond of.
Chapter Five: MagicThis chapter goes over how magic is handled differently in an Eberron campaign than it would be in standard D&D. The discussion quickly shifts to the Planes, of which there are quite a few -- far too many to try to list here. Suffice to say that some of the planes are actually pretty interesting. New Cleric Domains show up after that, including a domain for the Deathless (detailed in the Monsters section). New spells follow, including things like Control Deathless, Create Deathless, Feast of Champions, Magecraft, Inflict Critical Damage, and Return to Nature. There are quite a few spells here, and as with any Wizards product some of them are good, and some aren't. But there's more than enough interesting new spells to satisfy your game's spellcasters.