So flashed my phone using another carriers firmware.
I must say I am enjoying it.
All my functions work flawlessly i.e. WiFi, Bluetooth, LTE, calls, screen brightness, fingerprint scanner, speakers, all apps are running/updating etc.
Battery is VERY good!!!!!!
Yes it is missing key features but I'm not too worried about that. All issues in the forum regarding this update I am not experiencing at all.
I would recommend flashing using xperifirm and newflasher. It will wipe your phone so be sure to backup. Here is a tutorial I used. Farelly easy to use.
http://www.xperiablog.net/2018/01/28/newflasher-guide-to-install-new-firmware-for-xperia-xz-premium-...
I'm thinking that the OTA is a "dirty flash" that's why problems are occurring.
Also I'm using Lawnchair launcher which adds to experience.
https://www.apkmirror.com/apk/deletescape/lawnchair/lawnchair-2-0-698-ci-alpha-release/lawnchair-2-2...
My firmware version in the attachment.