I hesitated to install it being afraid i will brick my camera, as there are many warnings on the ML site, but if you follow instructions it takes only 5 minutes with no problems.

I have a shoot tomorrow and I need to focus peaking to work. Maybe I installed it incorrectly but I'm certain that installed it correctly. You will still be able to access all Canon functionality. The last time I had ML on this camera it was working just fine. Magic Lantern runs from the card, as an add-on over standard firmware. It is not a hack, or a modified firmware, but it runs alongside Canons own firmware. If your camera is on an old version, download and update. Magic Lantern is a custom firmware add-on for Canon dSLR cameras. Trap Focus: camera takes a picture when something comes in focus I just installed magic lantern but the focus peaking (the main reason I got ML) isn't working. Before installing Magic Lantern, check that your camera is running the latest Canon firmware (v1.0.9). The EOS M has the smallest buffer, the 5D Mark III the largest. I have installed it and i must admit i am very happy with some new cool features of my 550D, although most of new options are for video mode there are tons of new features for still shooting, some of the things you get : Canon cameras have a 100MB to 275MB size buffer for recording raw images. For all those who like to experiment with your camera possibilities and unaware of firmware updates,apart from official Canon fw there is a custom firmware called Magic Lantern /wiki/550D

Magic lantern canon 550d install