Although the plots and stories trailed off a little in quality near the end of the series, 'Hawaii Five O' in its prime was a remarkable example of how to do a television show right. It had a lot a factors going for it : Spectacular opening and closing credit sequences, a grabber of a theme song, exotic locations, a charismatic lead actor who had great hair and knew how to work it, and a racially diverse and intriguing supporting cast.
The series creator took a chance and had Jack Lord play McGarrett as a hard-nosed, hard-driving tough guy instead of a "Teddy bear" type, but this worked because McGarrett was so obviously committed to his job and to "Law And Order" that his brilliance and energy won the audience over, and in fact made them like him even more than if he had been played as a "Basil Rathbone Sherlock Holmes" character.
But the thing that sets Five O apart in my mind, is that whoever was in charge of story and script quality really knew their stuff and were allowed to do their job. H50 episodes had remarkably tight and internally consistent plots and screenplays. The screenplays always played fair with the audience, and almost always featured extremely clever plot devices, gimmicks or MacGuffins that made you admire the deviousness and ingenuity of the characters who were trying to do bad things under Five-O's watchful eye. And McGarett and his staff would scramble against a deadline to understand the gimmick and solve the mystery or the heist or the caper before the 'bad guys' could get away with whatever they were planning. And each episode was directed and edited with crispness and energy that kept everything moving and wasted no screen time.
Many times things were so interesting that the hour long show seemed to be over almost as soon as it started. You can't give a police detective show a much higher compliment than that. To manage to pull this off for so many years was a remarkable achievement.
Three cheers for "Hawaii Five O" and the people behind it. It holds up as one of the high water achievements of television drama.