While the visual design of Deus Ex: Human Revolution is excellent, the game's engine doesn't incorporate many of the complex graphical features found in games that have come out in the past few years. Simplistic lighting and shadowing models are common, and many of the game's textures give the world a somewhat sterile look. Whether you're playing on a PC with DirectX 11 support or on a console, the various versions of the game render in much the same manner.
The PC version of the game offers a few graphical options to tweak, and when switching from DirectX 11 to DirectX 10, the game removes access to tessellation, as well as more complex depth-of-field and shadow effects. The lack of these features changes the look of the game slightly, and in no way ruins the feel of the game. Playing the game with rock-bottom settings is completely an option.
High vs. Low Quality
As far as we can tell, post processing changes the way that light sources affect the overall look of the environment. When disabled, the blue from the monitor on the wall seems to take over the scene.
Tessellation is mainly used on character models in Deus Ex. It gives the models a rounder, more natural look. There are a few objects in the world that make use of the feature as well, but they're far and few between.
Simple lighting models beget simple shadows. Soft shadows give the edges a lightly fuzzed-out look. The difference between enabling and disabling shadows is readily apparent. Note that only the box in the scene loses its shadowing.
The vast majority of shadowing in Deus Ex comes from screen space ambient occlusion, or SSAO.
Depth of Field
Depth of field, as far as we can tell, is used only in conversational moments. Note how the backdrop around the character takes on an out-of-focus look. Many games also make use of depth of field when zooming in from a gun sight, but that is not the case with Deus Ex.
Console and PC Comparisons
There are few differences between the consoles and the PC. Aside from slightly different SSAO usage and resolution differences, the versions look remarkably similar.