Holy crap, I saw a film in a theater. Last time this happened...I can't remember. It could have been Pan's Labyrinth a year ago. This time, we were up in Pennsylvania with my parents to watch the kids, and we had two choices: Juno and Atonement. As it was my birthday, I got to pick, so I flipped a coin, and it turned out Juno.
Without giving anything away to those of you who still want to see the movie, I say go see it. The cast is great, and the movie is refreshingly focused on the girl, Juno, rather than on some pathetic inept "gee isn't it funny when two morons get together" schtick, which is what I imagine Knocked Up to be like. Although, if I had more movie time, I might try to see Knocked Up and think of ways to put those two films (and maybe more...hey audience, how many young adult pregnancy films are out there?) for some sort of course on comedy.
The music is dead on, although for all of Juno's mentioning of Iggy and the Stooges, not a single song from them exists in the movie or on the soundtrack...maybe they had trouble paying as much as Carnival Cruise Lines for the song rights.
You might also be able to put the film into the same category as Grosse Pointe Blank as a latter-day send-up of a John Hughes film. In fact, my wife said as much as we were watching it, saying early on that it was like a "more complex version of a John Hughes film." What makes it very different from GPB, which was clearly a parody of the Hughes formula, is that Juno only nods in the direction of the Hughes plot -- the lead character is a bit of a social outcast, but then so is the object of her affections, and the "third wheel" (usually a pretty but selfish and snobbish type) is hardly that. Additionally, the dialogue is smartly written, with Ellen Page playing a cynical, knowing teenager who still isn't an adult in teen drag: she makes serious mistakes due to her inexperience and puts things in ways that are both earnest and naive.
A great role for Jason Bateman, by the way.