It's not bad, but largely retreads narrative territory staked out in other better films like The Wolf of Wall Street and The Big Short.
And like both of those films, Pain Hustlers puts the blame for fentanyl addiction mainly on pharmaceutical company reps, while ignoring the more complex (and yet more significant) role the Federal Government and the War on Drugs has played in making it harder/impossible to get safer and yet actually effective pain medication, especially for people who suffer from chronic issues like Crohn's instead of cancer. It also places minimal blame on the doctors themselves, who were the ones actually prescribing the drugs at dangerous doses to people who didn't need them.
The pharmaceutical rep's job is to sell a product, they do not take a hypocratic oath and aren't doctors (usually), so if their drugs are being used off label in ways that are dangerous, it's really weird not to put the primary onus of responsibility on the trained, government licensed "experts" who are supposed to have a deep understanding of the effects of the drugs they prescribe, and who literally swear to "do no harm" or lose their license.
In the sadder of the drug in the film, it actually was quite effective and better than alternatives for late stage cancer patients, but the cost benefit of taking it vs. possible addiction and overdose risks are very different for someone who has a high probability of dying in months either way than for someone who is otherwise healthy.
Shouldn't we be most concerned with doctors?
But somehow these films never focus on that nearly as much as they focus on the companies themselves... And they never turn their shifts on the DEA, the FDA, or NIH, when they absolutely should.