Yes, this book is balanced. The Almighty One has declared it so.
"Why is that, your worshipfulness?" a lowly peasant asks his Almighty Lord about the Balance within Eberron.
The Almighty One looks down at his peasant, smiles, and speaks with a powerful commanding voice, "My child, the book Eberron, like ALL other roleplaying game books, is Balanced because....there is NO True balance in roleplaying games. It is wiser to just play the game how you want than argue over the semantics of what is right or wrong. Do you not see child, that to argue over something as trivial as game balance in a roleplaying game is to waste your breath and life and you could spend that time Playing the game instead of complaining about something that CAN NOT be fixed by ANYBODY."
The peasant looks up in awe, for the concept of game balance is now within his grasp.
Play the game how I want, the peasant thinks to himself.
And if I don't like something, the Almighty One has given me permission to change it however I want.