CEL says it can maintain strong connections, even in congested environments with interference from Wi-Fi and Bluetooth. Its +123.5 dB link budget enables higher data rates to be maintained for longer distances, but is said to maintain a long battery life due to its extremely low <1 uA (microamp) sleep mode power consumption.
Whereas most ZigBee modules run at 250 Kbps only, the MeshConnect module runs at 250 Kbps, 500 Kbps or a full 1 Mbps, enabling both higher speed applications as well as those that require a burst of throughput at key times. The MeshConnect module is unique in that it has a built in Codec processor that enables voice and low resolution video applications such as security cameras, walkie-talkies, and intercom systems.
More info here.