Tom Hiddleston once said in an interview that Kenneth Branaugh (sp?) wanted Loki to have a "lean, hungry look". I think this drawing achieves that nicely. The dark shadows make him appear wan and sickly, almost skeletal (the cheekbone protrusion is especially well done; Hiddles has insane cheekbones). This is a beautiful black and white portrait; well done!
Yes, I remember that interview. Tom has quite sharp features by nature but I noticed that in Avengers they cleverly underlined his bone structure with make-up to make Loki look even more thin and sinister. I think it worked well for the character.