Well,
I like the internal light, extra space and the easily removable lid. The removable lid is handy because now I can throw the fridge into the trunk of our Jetta and use it, before you could maybe sneak a hand in there before the lid hit the top of the trunk.
Also the newer ARB has a battery monitor utility that will shut down the fridge at a preset values, saving your battery. Also love the fact that I can now see what the temp is in *F instead of mentally converting to Celcius, and guessing wrong...
Still warming up to the plastic exterior though. And the feet don't fit the old ARB/Engel gear, so I'll have to get another slide lock, but you already knew that.