Each characterization technique is chosen on the base of which information you want to determine. AFM could provide the surface roughness, visualize defects such as dislocations, provide elasticity information....AFM studies can be found in a lot of papers, as well as by directly searching on Google, you can find amazing images and have an idea about its capabilities

AFM is a kind of microscope which in standard conditions (without vacuum or high temperature) allows to image the surface (as well as differences in material properties) with a magnification of up to 32,000,000 x (I have never needed more). Atomic resolution, nanomechanical, nano.... . Why do we use microscopes? To understand how matter works, how to design a better one, how exactly it degrades, what affects how to conduct production to make it safer.