Phenazepam is a great benzo, in my experience. It is mild, and the decently long half life make it great for day-time anxiety/social anxiety. Also good for sleep.
All the horrors revolve around the fact that it is incredibly easy to buy grams of pure powder via the internet, and people who don't know what they are doing and don't have a miligram scale will without a doubt end up dosing too much and blacking out, or worse. Since the dosage is relative to clonazepam in my experience, 1mg extra could make the difference between feeling good, and blacked out. 1mg is VERY difficult to even see, much less eyeball with any degree of efficacy. The only way to accurately dose it without a very accurate scale is to make a solution of phenazepam/propylethylene glycol. Even so it is still tough to get it to dissolve fully, and errors in accuracy are still very possible.
The compound itself is not the problem, it is just the same old story as with any other RC's that are active in the MG range, and add un-educated people/improper tools/scales/stupidity, and bad things are bound to happen..