A sterner, almost inhumane look which brings out a feeling of dread in the viewer. Less "frown-y and tired" more "angry demanding boss". Obviously Oscar's a human being and this is a different take on Apocalypse and heck, this is just a BTS pic, but Apoc's looking "weird" here, that's all I'm saying. I'm not analyzing the whole film and commenting on the facial expressions that an ancient mutant should have were he real based on a single still. 'Twas just a corny joke...
In the comics, especially in his miniseries, you see Apoc start out as a "weakling" of some sorts, a guy you can almost pity. But he slowly and steadily loses his "humanity" to become a stern, cold, calculating and cruel being with only one goal: Evolution through hardships. Thus far, I'm not getting that from this particular version of Apocalypse, but it doesn't mean that I can't enjoy a different take on the character...