Anyone Install Lithium ion Batteries? Results?

Not sure why some many are dismissing lithium batteries as not being safe. Is it because when you ship them you have to put a label on them that says "cannot travel in a passenger aircraft"? Well neither can lead acid batteries.
Does anyone ever consider the real dangers of lead acid batteries? They explode quite often, kind of like a hydrogen bomb. Just do a little web search for lead acid battery explosions.