How is that even close to a disappointment?

It's not an easy ending to interpret really. I have my own simple, unclear interpretation which ultimately leads to the meaning of the movie title but i don't think it's accurate so I don't think I will share it here

But like kobe said, it was the ending of the novel and the Coens faithfully adapted it (which I thought was very brave). But excusing the last few minutes, it was heck of a movie.