The S3 Neo adds 500 MB of RAM and Android KitKat. In use, this course benefits to the overall responsiveness since it must be admitted that only one Giga of RAM on the classic S3 was really the bare minimum ...
This is an excellent device with excellent image quality, SoC (all graphics-processor-RAM) very satisfactory price and content. Really a bargain!
It lacks only the 4G (it's far from essential!) But for that, there is the S3 4G: http://amzn.to/1DLq5cB