I once heard from a guy about a guy that that knew someone that lost his face and eyelids. The canister didn't seal properly and some static from his fleece jacket ignited it into a roaring flamethrower, right at his face. Shrapnel from the canister scalped him.
Long story short, his face was gone, the hair on the top of head never grew back, and his eyes dried up and shriveled into raisins without their eyelids. His wife left him (with the children, they couldn't bear to look at him), and he now lives in a small trailer outside of Hesperia, CA stockpiling ammo, drinking heavily, yelling at the mailman, and listening to Michael Crichton books on tape and InfoWars podcasts all day long.
Personally, I've been VERY VERY VERY lucky.
15+ years of using canister stoves and I've never had a single problem, ever.
But this is hardly the norm, you probably will never be as lucky as I am, and I have been known to live on the edge.