Normally, I don't mind the old cliche of boy gets the girl. It's relatively harmless. It's also timeless. "And they both lived happily ever after..." is probably one of the oldest plots to still exist. It's the stereotypical happy ending we all expect to happen in MOST stories. The good guy wins, kisses the girl, fade to black.
The problem with this cliche is that it makes the girl a prize, the ball, a piece of property to be won. And this sort of thinking makes men think that they each deserve a girl that they were even promised that there is a girl for each of them. And that can lead to ugliness in real life sometimes when a guy might think he deserves a girl...and she turns him down.
So I was delighted in Paper Towns when the main character is turned down by Margo at the end of the film who tells him "You don't know me. How could you love me?" and he lets her go but it's still a happy ending. He goes to the prom with his friends and Margo disappears into the sunset to follow her dreams and her own path. He respects her and loves her enough to listen to her wishes and let her go. He grows up and realizes that he was just idolizing her (and maybe being a bit stalkerish) and that the mature thing would be to back off and let her live her own life.
I've never seen a movie or read a book that ended like that and painted the whole thing as still positive. I thought it was incredibly refreshing and realistic and respectful toward women. I don't think books or films that have the old-school boy-gets-the-girl plot are necessarily BAD. I think there is a place for them and I like them in small doses. You can be critical of something while still being able to enjoy it. I just think that they have become a bit stale though and hope that more writers might go in the same direction as Paper Towns.