Works perfectly well in my 60D, I use the video features only though. Just drop the files on all your SD cards, install it like a regular canon firmware and voila. Remember not to delete the ML files from your SD card after you install it, as far as I know the files also need to be on the SD card for ML to work.
You can also still reformat your card in-camera without deleting the ML files, I believe it even says how on the camera menu.
Seems safe and stable in my 60D but keep in mind (if you use it for video) that you'll probably need faster SD cards if you intend to play with higher bit-rates and other heavy stuff. My cards seem to buffer and stop recording more often than before.