Ajax Plugin Not Echoing Response

This is the final code I am using. Thanks to webaware for pointing out that I was not using the correct datatype.

   jQuery(document).ready(function($) {
        $('.audience_intel_container .close').click(function(){
        $('.audience_intel_container').fadeOut('fast', function(){

        });
});

$('.audience_intel_container button').click(function(){
    console.log('clicked');
    var formdata = $('#audience_intel_form').serialize();
    $.ajax({
        type : "post",
        dataType : "html",
        url : audience_intel_js.ajaxurl,
        data : 'action=audience_intel&'+formdata,
        success: function(response) {
            alert(response);
            $('.audience_intel_container').html(response);
        }
    })
})   
});

php

add_action('wp_ajax_nopriv_audience_intel', 'audience_intel_ajax');
add_action('wp_ajax_audience_intel', 'audience_intel_ajax');
function audience_intel_ajax() {
$likeit = $_POST['likeit'];
$response = $_POST['response'];
$postid = $_POST['postid'];

add_option( 'testing_form_like', $likeit );
add_option('testing_form_response', $response);

global $wpdb;
$tablename = $wpdb->prefix . "intel";

$newdata = array(
    'radio' => $likeit,
    'feedback' => $response,
    'postid' => $postid
);

$wpdb->insert (
    $tablename,
    $newdata
);

$result = "<p>Finished successfully!</p>";
// json_encode($result);
echo $result;
exit;
}