Shakespeare's treatment of love in "Much Ado About Nothing" differs from his other romantic comedies. Sure, it shares the same stagy plot, which finishes with the lovers finally getting together, but Shakespeare also mocks the conventions of courtly love that were popular at the time.
Although Claudio and Hero's marriage is central to the plot, their "love at first sight"-type of relationship is the least interesting one in the play. Instead, the audience's attention is drawn to Benedick and Beatrice's unromantic backbiting. This relationship seems more believable and enduring because they are painted as a match of intellectual equals and don't fall in love with each other based on superficiality.
By contrasting these two different types of love, Shakespeare manages to poke fun at the conventions of courtly, romantic love. Claudio uses highly contrived language when speaking of love, which is undermined by Benedick and Beatrice's banter: “Can the world buy such a jewel?” says Claudio of Hero. “My dear Lady Disdain! Are you yet living?” says Benedick of Beatrice.
As an audience, we are supposed to share Benedick's frustration with Claudio's transparent, pompous rhetoric of love: “He was wont to speak plain and to the purpose, like an honest man and a soldier… His words are a very fantastical banquet, just so many strange dishes.”
Deception—For Bad and Good
As the title suggests, there is a lot of fuss over very little in the play-after all, if Claudio weren't so impetuous, Don John's rather weak plan to ruin Don Pedro's reputation and disrupt the marriage of Claudio and Hero wouldn't have worked at all. What makes the plot so intricate is the use of deception throughout, via trickery, lies, written messages, eavesdropping, and spying. Back when the play was staged, the audience would have understood that title is also a pun on "noting," or being observant, even bringing the deception theme into the title. (The words are thought to have been pronounced similarly back then.)
The most obvious example of deception is when Don John falsely slanders Hero for his own mischief, which is countered by the friar's plan to pretend Hero is dead. The manipulation of Hero from both sides renders her a passive character throughout the play. She does very little and becomes an interesting character only through the other character's deceit.
Perception of Reality
Deception is also used as a force for good in the play, as in Beatrice and Benedick's scenes where they overhear conversations. Here, the device is used to great comic effect and to manipulate the two lovers into accepting each other. The use of deception in their storyline is necessary because it is the only way they could be convinced to allow love into their lives. Phrased another way, the theme could also be called one of perception, or how truth can differ from reality. Both couples have to discover the true nature of their beloved.
It is interesting that all of "Much Ado"'s characters are so willing to be deceived: Claudio doesn't stop to suspect Don John's actions, both Benedick and Beatrice are willing to completely change their worldview after overhearing things about each other, and Claudio is willing to marry a complete stranger to appease Leonato. But, then again, it is a lighthearted Shakespearean comedy.