I started watching it last night. Dopesick was much much better. By now we're all familiar with Purdue pharma, the Sackler family, and what went down with Oxycontin. I think that Painkiller is worth watching just to see another interpretation of the events that unfolded that has had such an impact on our specialty.
That being said, Painkiller is like Dopesick but instead of good writing and well-done, it was made by Netflix.
It's full of rap-music, skimpy dresses, quick flashing scenes that are made just to shock you (i.e. flashes of Sackler named buildings in quick succession that you don't have enough time to read, a middle-aged DEA man dancing in small swim trunks that say Oxycontin on them, etc), overly aggressive females and weak men, strong black characters and weak white characters. I haven't finished the series yet, but given Netflix's politics I imagine there will be a gay scene not relevant to the plot forced in there somewhere as well. If that type of thing bothers you, you may not want to watch it.