We'll tell it to you straight: there's not a whole lot of humor in this one. The tone is pretty somber all the way through, and that makes sense, given what goes down in this play: children are killed all over the place; bloody handkerchiefs are waved around; people are stabbed and beheaded; people mourn a lot and prepare for death.
Seriously, folks: strap on your emotional seatbelts for this baby.
On top of that, Shakespeare really messes with our sympathies. Sometimes, we really do end up rooting for the most malicious and evil of the characters. Margaret is bloodthirsty and savage (at least until her son is killed in front of her), but her never-give-up attitude and ninja-like guts are something we'll admit we kind of enjoy seeing her play out. Same goes for Richard. We're completely repulsed by him, but we also admire him for his audacity, his wit, and his evil-genius political moves.
Almost everyone in this play has an axe to grind, and almost everyone in this play has an angle or a ploy. With all this scheming going on, and with all those revenge plots and high-stakes battle scenes, it's hard to keep anything straight, and our general code of ethics starts heading into breakdown territory. We might call this a morally ambiguous tone, or we might just say we're drawn in by all the crazy stuff that goes down in this play.