benzodiazepine's (xanax, valium, etc.) are a great way to potentiate the effects of opiates, or any other drug for that matter.
then there are the horror stories as a result of peoples newfound reduced anxiety. they feel 10 feet tall and their nervous system is depressed so inhibitions are out the window.
that said, I'd agree, they are the worst thing going in pharmacology today, not so much for what happens while your on them, but more so the withdrawal that can last forever.
I think its safe to say we both would agree on the phrase, "proceed with caution."