1) Import the OBJ at its base resolution. I'm assuming you want to use that head as a prop, and not a figure. So we'll go with prop.

2) Switch to the PROPERTIES tab.

--- Make sure Smooth Polygons is checked.

--- In the Subdivision settings, it defaults to no subdivisions for Preview and Render.  Start with the Preview wetting.  Increase the setting until you get the type of result you'd like in the final render.  THEN, enter that value in Render subdivisions.

--- Next, cut the Preview setting back down to 1.  You just need enough to take the facet look away. The higher you set this, the more taxing it will be on your system.

Try initially setting the Preview to 1. It SHOULD make it smoother. But the preview setting doesn't matter as much as your final render.  Plus, setting the Preview subdiv level too high will be taxing your system.

3) Choose Display > Document Style > Texture Shaded.  You SHOULD see a nice shaded model now. 

Can you confirm that you tried these steps?