Kamichu! is one of my favorite anime, so I decided to check out the manga version.
The manga did a good job of fixing continuity issues from the anime series (the anime came first, I believe), and taking out the stories that I felt were the weakest from the anime. Unfortunately, even though improvements were made in the story, I still preferred the anime, bacause the world and all of the cute spirits are just more charming in color. Also the manga added quite a bit of fanservice-y bits (bath scenes, weird "camera" angles, etc.). I can't figure out how some of those middle school girls got such huge boobs. But even though I found those bits a bit unsettling (they're in middle school!), my (possibly unwarranted)love of the story prevailed.