The Har'pengh is good if you are A) not going to fire it a lot because it has a long cool down, or B) don't have the boff slots for torp skills. Its a good cheap torpedo, but plenty of things outclass it at end game if you have torp skills, and sometimes even if you don't.

If you want to have fun, get the Romulan rep torp with three purple torp doffs. instant chain of heavy plasma torps, but the target will probably die before any of them hit. Still looks funny.