John Green's The Fault in Our Stars is a love story/existential meditation that happens to involve two teenagers with cancer. It's an essentially secular story about young people confronting death, which in and of itself is noteworthy, and it's also great—funny, philosophical, unflinching. I'm really looking forward to the movie; it stars Shailene Woodley, who was the best part of recent high school flick The Spectacular Now. (Not as in love with Ansel Elgort as Gus, I gotta say.) My excitement is not diminished by the first official trailer, though the precocious dialogue is a bit more jarring when spoken aloud than when read on the page.
I interviewed Green two years ago; read that here, for a sense of why teens (and adults!) love him so much.