Purely by coincidence, I switched on my Onda VI40 Elite last night and found it unbootable. Got a mini android logo, and nothing more. Didn't even get to the "bouncing android" animation. I have no idea what I'd done to cause this, but I guess that's the risk you take when your machine is rooted and you experiment with the operating system. I could only switch off the device by holding the power switch for ~10 seconds - but then, five seconds later, the device would turn itself back on and halt at the mini Android logo again! Thank goodness I can get the thing into recovery mode in my sleep these days. Perversely, it's somewhat reassuring to know that this device is almost impossible to brick. For the record, holding down the middle button, switching the device off by holding the power switch down for 10 seconds, releasing the power switch the moment the screen turns off and tapping the power switch three times put the device into recovery mode as normal. Despite appearing to be switched off, connecting the USB cable caused Device Manager to refresh and "USB device VID_1f3a_PID_efe8" to appear under the "USB devices" branch. Remember to unplug the device before running LiveSuite; it's the act of plugging it in that causes LiveSuite to commence the recovery process. Anyway, I digress...
I recovered to 1.2RC2 with a full format (bah). To cut a long story short, the 1.4RC3 OTA update worked from this clean 1.2 build - albeit via the "local update" option after failing validation on the "online update" (as mentioned by others). I hope future OTA updates don't require a clean build - that would render the OTA update completely pointless!
Anyway, after what seemed like the longest installation, and then the longest reboot ever, the machine started Android 4.0.4.
My view on 1.4RC3 is, generally speaking, very positive. The latest Android goodies (like Face Unlock) are present. At first I thought the machine was slow and sluggish. Maybe it was running some initialisation script or something: The machine eventually settled down and now it feels significantly faster and smoother than 1.2RC2. To be fair though, that opinion is subjective; I'd like to know if others agree.
The best news - making the entire procedure worthwhile - is that Wi-Fi performance is much, much better. The stock Android browser, whilst not the fastest, is acceptably usable and generates far fewer "Not Responding" dialog boxes.
The video streaming issues experienced with 1.2RC2 are gone. BBC iPlayer, YouTube/Vimeo etc. all seem to work well so far. In fact I'd go so far as to say that the Onda feels like a new and better tablet.
Google Play works better than ever, without any tedious fiddling about with configuration files. Angry Birds and Google Chrome were found and installed without problem.
It's too early for me to indicate whether the battery indicator reading is more reliable.
I have no real complaints with this firmware so far, except for the failed online update itself. I strongly recommend backing up your apps & data, and upgrading. My thanks to Onda for releasing what I consider to be an essential software update.