IMDB's "genre" line for this movie: "Comedy | Horror | Romance". Close enough. It's unexpectedly sweet for a zombie movie; I imagine it might offend purists who like their undead cinema grim, cynical, and hopeless. For my part, I thought it was clever and different.
The movie follows teen zombie "R"; he still has enough brainpower to think about his sorry state. (We are treated to his internal monologue, and it's pretty funny.) Inhabiting a derelict airport with his fellows, he spends most of his day shuffling through the concourses. He finds time now and then to visit his retreat: an abandoned passenger jet that he's tricked out with a stereo and collected knick-knacks. For a zombie, he's rather charming and sympathetic. But when hunger strikes, R and his zombie friends stagger off to the nearby city to find some living human flesh on which to feed. So that's a downside.
The remnants of humanity are led by authoritarian John Malkovitch, and they're all huddled in a city behind an immense circular wall. But they need to send expeditions into zombie-dominated areas for medical supplies; one includes General Malkovitch's lovely daughter Julie. The humans are attacked by R's zombie band, and there's a lot of death and PG-13 gore, but during the battle R is entranced by Julie, and instead of eating her, spirits her away to his jet.
Does an unlikely star-crossed romance blossom? Well, sure.
Checking out IMDB and Wired post-viewing, it was brought to my attention that there were a lot of intentional parallels between Warm Bodies and Romeo and Juliet. (Yeah, I'm a philistine, that totally went over my head while I was watching.) Fortunately for R and Julie, they weren't totally married to the R&J plot. But there's a balcony scene.