From a quick read of the code, it seems like all this does is shift pitch; it doesn't change resonance or anything else that affects how your voice sounds. So it's great for sounding like a chipmunk or a demon, but not that useful for sounding like a different person.

Looks like it uses libsox internally. You can also use command-line SoX utilities to get the same effect. For example, this plays your microphone back at you, pitch shifted and with a delay:

  play '|rec -p pitch +400 40 delay 5 5'

(To be clear, I don't mean to beat down anybody's pet project. Just spreading related information. There's very little accessible documentation of Linux audio stuff.)