I don't shoot video but I have used Magic Lantern since the early days (2010) on a T2i/550D for manual access to 1/3 stop ISO's, Kelvin white balance, focus patterns. These are features that Canon blocks in the Rebel series, but are actually still in the camera. I think it is worth it if you need the features it adds, and as far as I can tell it is close to 100% safe. AFAIK, no camera has ever been permanently bricked by Magic Lantern. Oh, I forgot this other neat feature I use, that is focal length display of zoom lenses.
Focus peaking could also be really useful for still shooters with manual focus lenses as well.