Multiple FIle Uploads Script [Secured]

<!Doctype html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Multiple File Uploads</title>
    </head>
    <body>
        <form action="" method="POST" enctype="multipart/form-data">
            <input type="file" name="files[]" multiple />
            <input type="submit" value="Upload File">
        </form>
    </body>
</html>
<?
    if(!empty($_FILES['files']['name'][0])){
        $files = $_FILES['files'];

        $uploaded = array();
        $failed = array();

        $allowed = array('jpg', 'png', 'gif', 'jpeg');

        foreach($files['name'] as $position => $filename){
            $file_tmp = $files[tmp_name][$position];
            $file_size = $files['size'][$position];
            $file_error = $files['error'][$position];

            $file_ext = explode('.', $filename);
            $file_ext = strtolower(end($file_ext));
            if(in_array($file_ext, $allowed)){
                if($file_error === 0){
                    if($file_size <= 2097152){
                        $new_file = md5(uniqid('', true)).'.'.$file_ext;
                        $file_destination = "uploads/".$new_file;

                        if(move_uploaded_file($file_tmp, $file_destination)){
                            $uploaded[$position] = $file_destination;
                        }else{
                            $failed[$position] = "[{$filename}] failed to upload!";
                        }//move uploaded files
                    }else{
                        $failed[$position] = "[{$filename}] is too large!";
                    }//file size
                }else{
                    $failed[$position] = "[{$filename}] errored with code {$file_error}!";
                }//file error
            }else{
                $failed[$position] = "[{$filename}] file extension '{$file_ext}' is not allowed!";
            }//in_array
        }// foreach ends here

        if(!empty($uploaded)){
            print_r($uploaded);
        }

        if(!empty($failed)){
            print_r($failed);
        }
    }

?>