In all my time playing, I've never taken The Black Star nor have I ever added it through console commands.. the closest I use to Black Soul Gems in general are Grand Soul Gems although I have used a few Black ones occasionally. I might consider using it for my current playthrough, but I haven't really thought about it yet.
It's the most reliable Soul Gem, period. There's never an end to bandits and thieves, and they'll always give Grand Soul. I'd thought that bears, being freaking bears, would give at least greater soul, but I get lesser instead, Black Soul never had such a problem