At worst the knot will get a bit loose from time to time (like maybe once a year), and then it takes a few seconds to tighten it again.
I expect my shoes will fall apart (they're already pretty old) before this knot unties.
[1] - https://web.archive.org/web/20051203081429/http://web.ukonli...
Super easy to untie, as well, if needed.
It's almost exactly like the "standard" shoelace knot I've used most of my life, but with just an extra tuck, and it virtually never unintentionally gets untied. It's fast, easy to put on and easy to take off. Highly recommended.
[1] - http://www.fieggen.com/shoelace/turquoiseturtleknot.htm