I have it installed on my camera and it's amazing. Monitoring audio during recording, manual gain, 1/8th stop isos, kelvin WB, everything is just great. It's almost impossible to brick your camera doing it, i have yet to hear of someone doing it to theirs. get the latest build and follow the manual/instructions.
The new software doesn't even write to the internal memory in the camera so you have nothing to worry about as far as ruining the camera. The software is simply referencing a directory on the card where the software is stored and it bypassed the internal software. When the camera is restarted it goes back to normal until you go to software update a click to reload magic lantern again.