To convert query string parameter values ($_GET, $_REQUEST), which include escaped Unicode values resulting from applying the JavaScript "escape" function to a Unicode string (%uNNNN%uNNNN%uNNNN) fast and simple is to use PECL JSON extension:
function JavaScript_Unicode_URL_2_Str($js_uni_str) {
$res = preg_replace('/%u([[:alnum:]]{4})/', '\\u\1', $js_uni_str);
$res = str_replace('"', '\"', $res); // if in str "
$res = json_decode('["'.$res.'"]'); // JavaScrip array with string element
$res = $res[0];
$res = iconv('UTF-8', ini_get('default_charset'), $res);
return $res;
}