Complete Champion focuses on the divine champion and provides new rules options for characters who enjoy battling for a cause, defeating foes with divine magic, and going on quests that mean more than simply defeating the bad guy and grabbing the treasure. Complete Champion also helps Dungeon Masters run quest-themed campaigns and adventures.
In addition to providing various archetypes for characters, Complete Champion includes new feats and prestige classes. This book features dozens of deity- and belief-themed organizations, turning religion and holy (or unholy) power into something characters of all classes can use.
A sourcebook for playing up the "divine" theme for campaigns. While it's obvious that the majority of the content will be meant for clerics, druids, and paladins, it does include little bits here and there for other classes looking for a divine bent. Overall, a rather interesting sourcebook with good options, but perhaps a little on the light side, compared to the other "Complete" sourcebooks.
Chapter 1 starts off with a treatment of churches and religions, presenting the churches (of the standard Greyhawk pantheon) as organisations that characters can be affiliated with (as per PHB2). The deities presented seem to be what you'd expect... although some of them, particularly Yondalla and Wee Jas, seem to deviate from what I thought of them - not that I'm particularly familiar with the core deities. There's also a large section on domain-specific affiliations, providing material for building up affiliations for other campaign/custom pantheons as well as no-deity variants. Although, as it usually the case, certain domains just seem to be quite a bit better than others.
Chapter 2 gives more options for characters classes, providing substitute levels to create a more religious or spiritual variant of each of the core classes. Most of them are pretty good options. The prestige classes on the other hand are pretty meh. Most are your 3-level and 5-level varieties. The problem with them is that they are so obviously created for the sake of supporting the 4 organisations presented in this chapter - basically, creating a prestige class just for the sake of having one. The organisations are good and flavourful. There's also your typical section of new feats, of which the domain-specific ones are quite interesting.
Chapter 3 showcases new spells, of which most of them are pretty weak and/or a waste of a spell slot. There a few that aren't bad, but unfortunately those exacerbate the problem that clerics are simply too versatile.
Chapter 4 comes the items. Some somewhat overpowered material components (for a small gold cost) are presented here, some special holy symbols that give a bit of a boost to different abilities, and some magic items, even a few magic item sets. Nothing particular stands out for me.
Chapter 5 provides some adventure ideas and also presents a few holy sites - places where you can get long-term bonuses by meeting certain prerequisites. There some value here, although I would say the locations are only cursorily presented, so DMs will still have to do most of the work. This chapter is pretty weak in that there could have been much more written about the topic of how to bring in the divine theme to a campaign.
In conclusion, aside from a couple of dislikes, it's actually not too bad for a sourcebook.
Nice balance of character options and flavor/backstory to shape into a campaign. (I really like RPG books with organization descriptions, because I can plop the organizations into my world with only minor tweaks. Makes for nice texture.)