Shakespeare writes great villains, and Edmund is no exception. He is charming, witty, cynical and so very much smarter than the people around him. He also starts off with a legitimate (ha, see what I did there?) grievance - being denied any share of inheritance simply because of his birth. He then goes a bit overboard in redressing that grievance, but you can't deny that he's thoroughly entertaining as he does so.
Also, Gloucester and Edgar? Both super-gullible.
Coming up on Monday we have an extremely short scene introducing Oswald, everyone's favorite slimy flunky. See you then!