If Johnny Eck running didn't creep you out that ending will scar you for life. This film ruined Tod Browning's (of Dracula fame) career. It was banned in the UK for thirty years after release due to content, but is now seen as a classic.
The point of the film, up until the sensationalist ending, was showing that the "freaks" were actual people, and the audience should not be irrationally afraid of them just because they weren't born normal.
Gooble-gobble, gooble-gobble, one of us, one of us...