I've been building my ZTE Open since pretty close to its initially release. I also use it as my daily device.
I bought a ZTE Open off of ebay back in April. My Nexus 4 broke in July. I have been using the ZTE Open as my daily device since.
I built from source (Boot2Gecko 1.4.0.0-prerelease) and, from my experience:
- Sometimes when I open an MMS message and click the back button, my phone reboots - If I open a content-heavy webpage or app the app will force close - Sometimes when I'm scrolling through the gallery app my phone freezes - Sometimes my handset earpiece doesn't work and I have to make calls on speakerphone - Sometimes the camera app freezes after taking a picture
Now, I'm not sure if these are issues with the ZTE Open's specs, the state of the build I flashed, or the method in which I flashed it, but those are my daily struggles using the phone.
That being said, as a phone (phone calls + sms + mms) it works, mostly.
I haven't been keeping it updated though. I should build the most recent and flash it soon.