I am using entity_metadata_wrapper for getting values from the user profile. Here is my code

'user_name' => $reply_wrapper->uid->field_user_first_name->value(),
            'user_img_url' => $reply_wrapper->uid->picture->value(),
            'title' => $reply_wrapper->field_review_subject->value(),
            'content' => $reply_wrapper->field_review_description->value(),
            'date' => date('d-M-Y', $reply_wrapper->created->value()),

How to get user picture field from user_wrapper?