Sometimes it will drop commits, add to many commits, not get anything at all, etc, when using --start-ref= and/or --end-ref= on io.js.
For example, to get the commits in nodejs/node#1383 (comment) I ran changelog-maker --start-ref=b8310cb --end-ref=08e89b1 iojs io.js, but it gets commits well before b8310cb also.
(This is the same issue I had trying to use this to make the 1.6.4 release before it was properly re-tagged.)