What3words has a severe flaw in that a simple typo or mix-up can be miles off from where you want to be...
It's a great idea though, but I'd suggest using "Plus codes" instead - similar principle, but adds some numbers, and support is already built in to Google Maps which most people already have handy and use.
I know some folk are a bit anti-google (fair enough) but PlusCodes are Open Source, so can be used without them, where as what3words is a proprietary system owned by a less helpful company.