Useful IMHO - can't beat having a bit of gucci string knocking about. My buckle is a whistle version - I was walking the dog in some woods a few months and came very close to turning my ankle in a rabbit hole. I didn't have my phone or EDC with me and it got me thinking about how I could summon help - whistle on my paracord bracelet never leaves my wrist now, unless I'm working with machinery.
Also a good 'combat indicator' of a fellow bushcrafter / EDCer etc!
"There aren't many problems that a cup of tea or a pint of beer won't solve...."