It's a testament to their acting and Whedon's directing that the old time speak fits nicely within the modern setting. In the wrong hands it could have gone horribly wrong. But here it just seems to work. Since this story has been around since before any of our great grandparents were even alive I won't dive into the plot like I normally do. I'll just stick with the actors and their work.
The film was shot in Whedon's home. The scene where Benedick is sitting next to a dollhouse talking serious is beyond amusing. As it is when he is rolling around on the ground trying to listen in without being seen. Densiof plays funny well. It's something that he showed us on Season 3 of Buffy and the first season or so of Angel before he became a badass.
Not to be out done, Amy Acker's performance is also chalk full of physical comedy that cracks you up everytime you watch it. Whether it be the first or 31st time watching it. She can bring humor and comedy in the same scene it is truly a skill and don't get me started on when she plays with the heart strings. I know it's not this movie, but try watching Angel A Hole in the World and not crying. You're heartless.
Nathan Fillion also brings a great deal of humor to his role with Tom Lenk as his faithful sidekick. If they had a few more scenes it would be safe to say they stole the movie. As it is they stole every scene they were in.
Over all this is an amazing fun movie. Shakespeare fan or not.