1. The plot was not Shakespeare's original idea
Shakespeare used as his main source for the Claudio-Hero plot a story from Matteo Bandello’s Novelle (1554–73);
2. Potentially The First of The Everpopular ROMCOM Prototype
bantering couples and the happy comedy ending on the surface.. assuming you don't interpret the ultimate love ending as trickery
3. Character Types are Sketched in This Play
We watch Shakespeare shake out some of the plots, character types, and methods he’ll later use in both his comedies and tragedies.
4. Don John Was a Bastard Literally and Figuratively
The illegitimate brother of Don Pedro; sometimes called “the Bastard.” Don John is melancholy and sullen by nature, and he creates a dark scheme to ruin the happiness of Hero and Claudio. He is the villain of the play; his evil actions are motivated by his envy of his brother’s social authority.
5. Claudio Mistook His Beloved Hero for Her Nurse, Margaret.
It was actually Margaret on the balcony!