Two @Quiqup drivers raced across London to compare delivering to 3 word addresses against delivering to street addresses. Read the article here: https://hubs.ly/H0b5h0m0 pic.twitter.com/Pdmh15cSBW
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
They're not memorable or easy to communicate. what3words is based on coordinates, it just takes those long strings of numbers and letters and converts them to 3 simple words.
Fair enough! 
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.