I really should not be mentioning the name of the book, but the first time I read it (during my under-grad days) I almost concluded that data structure was a bad course to pick.

Which brings me to the question I am asking here. What makes a programming or data structure or algorithm book tick?

Clearly, lucid explanation is one. But I also realize that organization of the material is very important and so is diagrams. What else? Some pointers would obviously help when I hang out in my neighborhood computer book shop the next time.