You can use console.log() in Firebug or Chrome to get a good object view here, like this:
$.getJSON('my.json', function(data) {
console.log(data);
});
If you just want to view the string, look at the Resource view in Chrome or the Net view in Firebug to see the actual string response from the server (no need to convert it...you received it this way).
If you want to take that string and break it down for easy viewing, there's an excellent tool here: http://json.parser.online.fr/