The Moto Z lineup got off to a rocky start with the original Moto Z lacking a 3.5mm port. Motorola also explicitly announced that they would be discontinuing regular security updates, which added to the worries.
The update also brings the device’s security patch level to November 1. It also enables Daydream mode, joining the handful of devices to support Daydream, other than the Pixels. It also brings Camera API 2 support, allowing camera applications to take advantage of the extra control.
The download is a hefty 1.58 GB, so you might want to download this one over a WiFi connection. These OTA’s take time to roll out to all devices to ensure quality control.