Well when there aren't any tanks...you use it as an anti-infantry unit. When you drop down near open topped vehicles, you put the flamer on 'em and take the two automatic S5 hits per open top you can hit. If it's say a single Falcon you use the bolters on it, and just clip the vehicle with the flamer and flame something else.
Space Wolves have requirements in the list that require you take points away from the drop pod concept, and take other stuff instead. This is "bad" for what you want to do.