It is an art and a science at the same time. Getting your story across from your solution into the minds of your audience can be very difficult. Effectively getting this job done is even more difficult. Visualization though is a very powerful tool if it is done correctly. Complex data and information becomes easily understandable and usable.
Humans are, without much effort, very capable of identifying differences in colors, shapes and sizes. For instance, we all associate red with being bad and green with being good. Leveraging this capability is the power of data visualization.