One critique of these types of films is that the protagonists, generally mopey self-perceived intellectuals, can come off as annoyingly pretentious (esp. Igby Goes Down). While Oliver fits this profile, Submarine's tone and dry sense of humor keep it from getting in-your-face. It does the whole bittersweet teenage love thing pretty well too. Just watch the stupid movie.
Here's a great scene where Oliver's mother questions him after he gets beaten up to defend his lady's honor: