I thought this movie was beautiful. 

It is, and what makes it beautiful is exactly the things those who don't like it criticize.
Either
1) That bitch old
Or
2) That kids a punk bitch
But the film is about those who society has thrown out as being unlovable finding someone who understands and cares about them.
Are they both flawed humans? Of course. But it's through the acceptance of these flaws that we see what is loving and needing of love in both of them. And this should make us feel more humane as a result.