This film has the reputation as the serious one in the series, but really its just as comic book-y in its way, despite the respected Wendell Mayes writing the script. That's not to say it's not effective - this movie has one of the all-time great concepts, a Western updated for the modern day: Charles Bronson is a liberal, peace loving architect until some hoods attack his wife and daughter, killing the wife and raping the daughter, leaving her in a comatose state. A business trip to Tuscon goes so well that creepy client Stuart Margolin gives him a gun - which Bronson then uses on New York streets.
Bronson's first killing results in him throwing up in shock but that's as complex as the film gets. All the people who try to mug him deserve to die, really - they giggle and hoot and pull out switchblades; there are no scared kids, or clearly wacked out on drug types; Bronson never accidentally shoots an innocent bystander, or inspires vigilantism which kills innocents. He just gets the crime rate down and inspires little old black ladies to stand up for themselves. The film is an add for vigilantism.
Having said that, part of me did enjoy seeing Bronson blow away these over acting muggers - it's wish fulfillment. The attack sequence on his family is genuinely shocking (a young Jeff Goldblum among the attackers... randomly spraying paint on the daughter's arse)... and it felt real that Bronson never gets to wreck vengeance against them. It's got a great grimy 70s New York feel, a superior cast (including Hope Lange as the poor wife).
The thing I remember most from it - Bronson's son in law calling him "dad" all the time. Bronson is effective in the role - he actually could act, he did all the time in the 60s, it's just he got out of the habit; but it works in the early part of the film when he plays "everyman".