It just doesn't work
I love it when Shakespeare is told in a modern setting. I think more people are willing to be exposed to Shakespeare when it's told in a modern setting. I think there's so much room for creativity and plays on the modernity and Shakespearean language. Romeo + Juliet with Leonardo Dicaprio and Claire Danes is a great example. A modern setting and feeling pulls you in with the great combination of the Shakespeare language pulling you slightly out. It works in Romeo + Juliet, even though most teenagers don't want to get married after first meeting and most people don't get banished today, the whole thing is perfect and keeps you in. Rival gangs/families feuding. Parties you wish you were at. Fast cars. Romeo and Juliet saying their famous lines in a swimming pool. It's great.
But here's my problem with a modern Much Ado About Nothing. It doesn't work. You're getting pulled out by so many things that it doesn't feel right anymore. The classics Shakespeare comedy traits of mistaken identity, tricks, overhearing conversations, etc don't work best in Pasadena, but in a theater or when it's actually presented as a period piece like the Much Ado About Nothing with Emma Thompson and Kenneth Branaugh. But chic, waspy people that listen to contemporary jazz in Pasadena don't fake funerals and deaths, worry about honor and virginity in a wife, expect someone to kill another for dishonoring a loved one, have princes, or have police officers arrest people for scheming and ruining weddings. It's all too much that pulls you out. Or at least that's my opinion. Whereas I think stories like Romeo and Juliet with violent teenagers with guns and fast cars, or Anthony and Cleopatra as current world leaders, or a Hamlet today works. The stories and language in a modern setting pull you in more because you feel like these characters, emotions, or events could happen today but you're still aware that all the better it's Shakespeare. These plays that your friends complained about reading in high school might suddenly jump off the page for them even though it's the same words and story they read back then.
But Much Ado About Nothing in Pasadena? No. I think that's why people left the theater when I saw it. However, I still enjoyed it. I think a lot of the people were miscast. A lot of the play's great dialogue, monologues, and wit fell flat and short with the actors' delivery, especially Amy Acker (Beatrice) and Alexis Denisof (Benedick). The entire play mostly rests on Beatrice and Benedict so if they fall flat, it's hard to enjoy the rest of the story or even care about them if they can't even get the banter and wit right. And that's the main problem with Wheton's Much Ado. Black and white film and furthermore acting ruins it. Much Ado is a comedy because the lines itself are funny when delivered properly. You don't need to add slapstick comedy to make it funny. Beatrice and Benedict going at it and the little one liners are what make you laugh and make it all believable. But black and white Pasadena with unnecessary slapstick comedy that doesn't make you laugh with all these Shakespeare elements that don't fit pulls you out. I like that Whedon used Fran Kranz (stoner Marty) from Cabin in the Woods. I was pleasantly surprised when I recognized him and I'm glad he's getting more exposure and did such a great job. However, maybe I'm too nit picky and no one felt this same way and thought it all worked perfectly and didn't feel "pulled out," but this is my interpretation and I'm wondering if I'm alone.
I encourage people to watch the 1993 version of Much Ado About Nothing with Kenneth Branaugh and Emma Thompson to compare with this film and Amy Acker and Alexis Denisof. Maybe you won't agree, but I think it's interesting and worthwhile to compare the differences for better or for worse.