The LCD display is stable enough for now that I don’t need to keep an eye on it (using a separate program to update it sorts any glitches out by re-initialising it).

However the brightness is just not right. The LCD was intended to be used with an Arduino board so expects +5V VDD, however it only receives a +3.3V VDD from the RPi.
Powering the LCD with +5V but using the +3.3V on I2C bus was not working.

I’ve therefore purchased a Bi-directional Logic Level Converter (HERE), hoping to power the LCD with +5V and use the same voltage on the I2C bus at least at the LCD side:

4-channel Bi-directional Logic Level Converter

I should hopefully set this up shortly and will update my findings here.

[Update – 30th Dec 2013]

The Logic Level Converter doesn’t do the trick. The LCD does not get recognised by the Pi. I’ve even tried to power it via a diode to drop the power support from 4.6V (read from a multimeter) down to 3.9V (0.7V loss via the diode), but the Pi still does not recognise it. I’m starting to think this is a poor LCD, but it can still be read when powered by +3.3V, even though it’s a bit dimmed.

[Update – 3rd Oct 2016]

I know I had many issues due to the breadboard as the LCD would even dim for half a second if a loud sharp noise was made close by. Since I have a Humble Pi, everything is a lot more stable, so I thought of revisiting the Logic Level Converter avenue, and it’s all up and running smoothly now 🙂

Oh and I’ve also got a custom case 3D printed, see this post for more info…

LCD with Logic Level Converter