When companies release products they normally reserve new prime decimals for substantially new products and sub-decimals for updates. Android 4.2 was a leap over 4.1.x. Android 4.2.2 was for housekeeping and bug fixes. It makes sense that 4.3 should be another leap. Yawn.
Most of the changes will not be evident. There is no new user interface (UI) to annoy developers (e.g. iOS7) and no new amazing features, unless you count harnessing new Qualcomm and Tegra chipset features like Bluetooth 4 and 64GB micro SD support. In fact, it has been postured that 4.3 was rushed to market to support Google Glass and smart wearable devices which are not quite working well with earlier versions.
There are changes in Wi-Fi and wireless charging and the camera app gets an update.
What is epoch making is that Google has released more ‘secret sauce’ - application programming interfaces or APIs that open up 4.X to more external developer use. For the most part these work with Android 4.0 and later, taking the pressure off app developers to update their UI and apps.
It has also taken the pressure off releasing Android Key Lime Pie V5.0, which will be epoch making, and will change the Android landscape at the expense of perhaps backward compatibility and app developer’s sanity.