Good film, bad ending! (spoiler)
The main character give a false confession about killing a little girl and goes to prison? What the heck? Who would do that? No one would do that. That's just crazy.
This ending totally ruins the character arch. Ask yourself, what was the character development? What did he learn trough out his journey? Nothing apparently. He doesn't overcome his inner struggles nor the external conflicts. He starts being a troubled young man making bad decisions and ends with making even worse decisions!
I usually like films about criminal with a heart of gold, tries to do all the right things in his life, but ends up dead or in jail, but this end is no good.