I'm using Firefox OS 1.3 on my ZTE Open and I've got to tell you that this is soooo much better than the version that shipped (1.0). There are some still frustrating issues, especially with the touch recognition but for an $80 smartphone it's not so bad. I'm glad there's finally an official version.

These instructions worked for me to install Firefox OS 1.3: https://blog.non.co.il/index.php/zte-open-phone-upgrading-to...