Usage for developer
require_once($JPATH_SITE . "/administrator/components/com_akismet/akismetJoomlaAPI.php");

//instantiate
$JoomlaAkismetAPI = & new JoomlaAkismetAPI();

$oracleDecision = $JoomlaAkismetAPI->isCommentSpam($commentPermalinkURL, $name = "", $email = "", $url = "", $comment = "")

if  ($oracleDecision) {
   // store the comment but mark it as spam (in case of a mis-diagnosis)
} else
{
   // store the comment normally
}

Your backend panel should allow administrator to review comments mark as spam, If You decide that a comment is falsely reported as spam, consider giving a feedback to Askimet by calling

$JoomlaAskimetAPI->submitHam($commentPermalinkURL, $name = "", $email = "", $url = "", $comment = "");