This is one of my favorite features about iOS 8. It works well, and you can put in a lot of stuff. Do note that you can only see this if you use a passcode to lock your iPhone, but you are doing that right?
One thing I added to the medical notes section: a reward for returning my phone.
I showed this to a coworker when iOS 8 launched and his response was: who will ever find that? Indeed it is a bit hidden, but iOS is so prevalent that I suspect it won’t take cabbies, or EMTs long to be knowledgeable about this.