I used to watch the reruns of this series on TNT before they started putting them on Wednesdays between 1-5am. This is one of the shows that just stick with you, the stories and the way the various characters all function together on screen is what helps to make it a classic to me.
The series follows the career of Andy Sipowicz, and other detectives in the 15th precinct. As the main character, Andy is a pretty interesting man, as the series progresses you see him overcoming various hurdles in his life. The first is his alcoholism, and is a constant theme for this character throughout the series' run. The second hurdle is his Racism, one particular scene after a confrontation with a woman stuck with me. Andy was in the squad's bathroom, rather upset that the lady told her daughter to hate him because he called her father a Racist name. Andy's lamentations during that scene were what stuck with me the most.
Other notable characters always end up paired with Sipowicz, such as John Kelly (David Caruso), Bobby Simone (Jimmy Smits), Danny Sorenson (Rick Shroeder), and John Clark (Mark-Paul Gosselaar). I loved different things about each character, though unfortunately Clark was the blander of Sipowicz' partners.
Overall, the series will always be a Classic to me, and I would recommend anybody who is interested in police drama to watch it. 10/10
Also, the lingo in the show is just cool.