Along with the improvements to the camera, the update will improve the accuracy of the phone's touchless controls and eliminates the chopiness that occurs during some phone calls. In addition, the Motorola Migration Experience is improved. That feature lets you move over photos, videos, texts, call lists, SIM contacts and more from your old Android phone to your shiny new Moto X.
Another improvement included the elimination of a bug that affected Motorola Assist, which lead to the reading of text messages at inopportune times (we could have a field day with that one). The update also adds a 30 day expiration date to the Google Drive 50GB offer, and fixes a problem that sometimes prevented a lost Moto X from reporting its position with the Moto Care Lost Device Finder service.
As usual, it is suggested that you use a Wi-Fi connection to download the update and to make sure you have a sufficiently charged battery. A 50% charge should suffice.