By now, most people should have understood, that R is a extremly powerful programm to calculate all kinds of statistics - though someone still has to implement Bowkers test. What might be less well known is that it has many extremly flexible built-in functions and well supported add-on packages to generate graphics.
Sheldon might say:
“R uses the worlds most powerful graphics chip - your imagination”
Or put differently the real advantage of R over the drag-and drop approach SPSS uses, is that it let’s you use your brain to develop new graphics.
Excellent introductions can be found here:
The basics graphs are well covered on my favorite R-site: Quick-R
A library of graphics here
Tips for visualizing categorical data and the package of the same name can be found here
Cons: …so far: We have no idea! ;-)