This movie was heavily marketed as a retelling of Shakespeare's "Romeo and Juliet," but the first thing you need to know is that it is only very loosely based on that tragic play. For one thing (Spoiler!) no one important dies in the end. In fact, people who were dead actually come back to life. (But I bet you saw that one coming.) Apart from the female romantic lead's presence on a balcony, and a few of the names (Julia = Juliet; Perry = Paris; R = Romeo), it doesn't bear much of a resemblance to the source material. There is no nursemaid, no priest, no apothecary, no Mercutio or Tybalt.
That said, I really enjoyed this movie a lot. In fact, I probably enjoyed it way more than I should have. The Husband wasn't super impressed, but that's ok. You have to appreciate the film for what it is: a goofy, though gory, Zombie Apocalypse movie that doubles as a romantic comedy. It's not going to go down in history as a film for the ages.
R's internal monologue is hysterical. "I'm dead. That girl's dead. [Gosh] these people look awful...[Man,] we move slow. This is going to take a while." And just as he's about to take a huge bite out of dude's arm, he pauses for a moment and remarks, "Nice watch." Another reviewer that I read somewhere (I have no idea where, sorry) remarked that it was a metaphor for young teenage love. I found this to be a delightfully apt description. R tells himself, "Ok, don't be creepy, don't be creepy," and then he turns around and looks at the girl with his staring undead eyes and goes, "Uuuuunnnngggh." Classic.
Also, R the romantic Zombie is played by Nicholas Hoult, who is adorable.