Pretty cool. You can achieve similar localization accuracy with WiFi, BLE, ZigBee, or long-range RFID. Common techniques are time of flight (ToF, or time of arrival), FMCW ranging, fingerprinting, or signal strength modeling.

Depending on the method used, the limitations arise from (a) needing to know ground truth location of beacons; (b) any necessary training steps; (c) multipath issues; (d) synchronization; or (e) other non-ideal RF artifacts.

You can also combine multiple sensor measurements over time (eg. a person's path) using bayesian inference techniques (ie. particle filters) to further improve location accuracy.

(This topic is related to my PhD thesis: mobile robots finding and interacting with long-range RFID tags in homes. Many of the techniques are akin to radar: http://www.travisdeyle.com/research.html)