the Android JSON is very functional, but has not bells a whistles. Where as GSON allows you to specify mappings between your classes and their json representation. It also has very nice automatic conversion of any primitive values to json, with no additional work on your part.
The payoff with GSON is if you have a lot of JSON communcaion, or complex objects that require value checking to prevent illegal values (such as NaN) and other cases where java-to-JSON is less than straight forward.
But if you just need to send and recieve a simple json object, the native library does the trick quite respectably. I am using it in my current project to post high scores to a server.
