The second Death Wish film has a very strange concatenation of qualities. It can come dangerously close to running off the rails altogether, but overall, I think it's a more successful film than the first Death Wish.
The first peculiarity is that much more strongly than the first film, Death Wish II's urban crime-ridden backdrop is exaggerated to a point of caricature. Of course, there was plenty of crime in Los Angeles during this era, but not as depicted here. This is almost Broadway-style crime, with choreographed gaggles of hoodlums running out of control in designer gang-wear, making spectacles of themselves. It's over the top but serious in a way that feels uncomfortable at first, but then, that's just the point, and it helps anchor the plot developments that follow.
And that plot should be no surprise to anyone who first watches Death Wish I. Death Wish II follows the plot of its predecessor as if it were a fairly rigid template. Even the events that cause Paul Kersey (Charles Bronson) to take charge and clean up society's scum by his lonesome are very similar. I don't see this as a flaw here (as I don't in many other sequels that use a template approach, including series like Friday the 13th). This is a direct continuation of the story of the first film, and the similarity gives Death Wish II both a natural, logical flow and a nice symmetrical structure.
Although Death Wish I had its brutal moments, Death Wish II amplifies that atmosphere and sustains it through its length. Like the films that best display gritty 1970s New York City--such as Taxi Driver (1976) and Basket Case (1982)--Death Wish II makes you feel almost dirty (in the grimy despair way, not a sexual way) while watching it. It's ironic, maybe, that Death Wish II does this so well when the setting is Los Angeles as opposed to actually being New York City, as in the first film. That director Michael Winner is able to perpetuate that atmosphere, whether by accident or design, results in the viewer being sucked into the setting and vicariously experiencing the range of unpleasant emotions felt by both the protagonists and the antagonists.
Also helping on that end is the score, provided by Led Zeppelin guitarist Jimmy Page. Although Winner sometimes incorporates Page's music in a discordant, jarring way--over the opening credits when it fights for volume with radio banter, for example--more often than not the score gives Death Wish II a sublime, otherworldly and eerie edge. It's too bad that Page didn't go on to score many more films.
This is certainly not a film to show during family time, and it's not particularly uplifting or overflowing with positive messages or socially redeeming values. But it's not trying to be any of those things. It's just a visceral (especially on an emotional level), disturbing revenge flick, and at that, it meets its goals well.
