On the web - try Rotten Tomatoes (93%) or IMDB (8.3/10 or 135 in the top 250 of all time).
These are both high scores, and reflect Juno's wit, sensitivity and overall accessibility. (IMHO)
What I would say is that I loved the film, but it didn't leave me with a particular lasting impression (in the way that, say, Pan's Labyrinth did).