I don't have what you might call "high standards" when I watch movies, I try to get my money's worth and check my cynical a-hole side at the door (note the word TRY... not always possible).
That being said, Juno was a great movie. A lot of people have praised the acting but I think the writing is really good too, the characters are drawn in such a way that their bizarre characteristics are very strong and obvious, but they never feel like completely fabricated characters. I'd say it's like a Wes Anderson movie, except that people don't all act like they're on some form of lithium.