How do I love thee, Warm Bodies? Let me count the ways.
First, I love your slyness. Like how you work in references to Romeo and Juliet (the protagonists names are Julie and "R" and there's a good balcony scene) without hitting us over the head with it. How you show the zombies meandering around the airport while R thinks about how it must have been in the old days, when people could connect with each other and interact, and then cut to a flashback of people meandering around the airports with their heads dropped down, riveted to their iPhones---a flashback so quick you could miss the joke if you weren't paying attention.
Second, I love your leads. Nicholas Hoult has it all: the perfect slouch, a great way with a comic line, and the rarified art of acting with your eyeballs (which is about all he's got to work with for the first half hour of the film). Teresa Palmer has the casual naturalness and attitude of Kristen Stewart with the dewy sex appeal of Scarlett Johansson.
Third, I love your humor because it's subtle and quiet. I like a good Melissa McCarthy scene as much as the next girl, but it's refreshing to be have jokes sent your way like a wink, quick and light.
Quick and light, too, is the moral of the story, that connection makes us human, that most (but not all) of us are salvageable if we try. There are no big speeches and no lengthy wrap-up. Just an image here, a line there, and the trust that the audience can put it all together.