I really liked this movie as Jon and I were watching it (in a real theater!): the main characters were sweet but also funny and sarcastic; the music was good; it took place in a realistic, less glamorous New York that was refreshing; the romance was uplifting and believable; and it was just plain funny. But I liked it less after it was over, mostly because I'm a little old-fashioned, I guess. And maybe sheltered, too. Maybe in comparison to those raunchy rated-R movies that target teen audiences (which I've never seen), Nick and Norah is no big deal.
In any case, I got on my parental high horse after it was over and I thought of all the teens who will certainly see this movie. There are some good things about it--some straight-edge kids, who are clearly smarter and cooler than the friend who gets so drunk and lost and is truly ridiculous (but funny); the good kids trump the bad kids in the end; etc.
But why can't they just make out at the end? No, they don't have sex (or anything else that includes the word "sex"), but what they do is kind of weird and seems out of place. I applaud the sentiment for married couples, it was just weird for two kids who'd just met hours before.