Very good writing and very good camera work, in both angles and continuity. This show is still viewable by today's standards. Some may appreciate how 'car phones' were the leading edge of technology in the late 1960s and early 1970s when not even fax machines existed. Others may reminisce on the occasional fad fashion statement even while the main characters wore what was considered conservative. Few can ignore how thoughtful the episodes were. Sometimes complex, the well scripted plots often kept the armchair detective puzzled until the very end. It is as though every single object, mannerism, and facial expression had a purpose towards telling the story.
Hard action, yes. Violent, maybe. Graphic blood and guts, no. Realistically, cars didn't flip over other cars and burst into flames at every car chase. Just like everyone experiences similar issues within each respective profession, some plots had similarities but they were so well thought out that they were very different in the end. Consequently, soft and caring moments were interspersed with happiness, sadness, and action. It was a fairly real show with few, if any, stupid scenes; a show where people didn't do superhuman stunts. It contains mystery and some suspense. The theme song is classic. It's a good series that can still be enjoyed today, on reruns, of course.