Broken Base: One half says that the episode is terrible for being darker and scarier than usual for the show and that the issue the episode was trying to tackle was handled incredibly poorly, while the other half says it's a brilliant episode for taking a series, dramatic turn and exploring a serious issue that the show often mocks (usually in cruel ways) and proof that the show has a soul underneath the Comedic Sociopathy.
For one, Brenda is shown to be undyingly loyal to her abuser, but neither give any reason why. In most cases, it's a case of Draco in Leather Pants, where the victim sees past the abuser's abundant flaws to whatever made them fall in love in the first place, but it's just as often the abuser threatening to kill or withhold money from the victim if they leave. This, plus Jeff showing no redeeming qualities whatsoever, makes Brenda look like an idiot.
Jeff, as with most representation of people the writers dislike, it portrayed as thoroughly stupid and cruel in a primal way, despite especially bad abusers usually harming people in crafty and very specific ways that they know will hurt them the most.
Joe claims that he can't incarcerate Jeff until Brenda files a complaint, which is unfortunately Truth in Television with most cases of domestic abusers, as they tend to do everything behind closed doors and are very subtle in their emotional attacks on their partner. In this case, it doesn't work, because Jeff has repeatedly beaten Brenda in front of other people, in plain sight. And when there is obvious evidence of abuse, a complaint doesn't need to be filed first to get the abuser arrested.
Finally, the gang decides that the best idea in the end is to simply kill Jeff, freeing Brenda, who is clearly psychologically damaged and has learned nothing from this ordeal.
The Mysterious Mr. Enter, himself a victim of abuse at the hands of his parents, said in his review of the episode that the staggering amount of misinformation on the subject was actually worse than no information at all and such carelessness was harmful to actual victims of abuse (he put a link to a support line in the video's description to show just how seriously he took this, then did a follow-up video debunking the common stereotypes of domestic abuse, passively mentioning that the episode would have been no good either way).
Moment of Awesome: Quagmire surviving getting strangled (as he's sexually asphyxiated himself so much that it doesn't bother him anymore) by Jeff, then running down the bastard with his car and slamming him into a tree.
Also kudos for the show playing domestic violence straight and for drama after over a decade of playing it for laughs. And to think it came from a tasteless joke on the episode "Jerome is the New Black."
They Wasted a Perfectly Good Plot: When Quagmire and Jeff were fighting in the woods, Brenda could have pulled a Big Damn Heroes moment by showing up to stop Jeff and save her brother. She doesn't, which is a shame, because both averting this and her crying over the...um, "note" that Jeff was leaving her, only furthers her Extreme Doormat status. That's...a problem.