What? I used to hate the idea of these, but my absolute favorite thing about this medium is the ability to turn fairly boring subjects into hilarious, fascinating stories.
For example, are you interested in your child getting familiar with Shakespeare? Try Marcia Williams. She writes a series of books that are comic-strip retellings of all sorts of fabulous tales: Shakespeare, Robin Hood, the bible, Greek Myths, the Iliad and the Odyssey, King Arthur and the Knights, the stories of famous inventors, and more. All of my kids, and I mean ALL of them, ages 3, 5, 7, 9, and 11 love these books. They are teaching them fabulous stories in a fun way and she really does not massacre these stories. The essential content is completely there.
And here's another great series: Good Times Travel Agency. They have books on Greeks, Vikings, Egyptians, Ice Age and so forth and my kids love these too. Love them.
Our final favorite history series is the You wouldn't Want to be a series: