Unlike some other 1970s shows (I'm thinking mainly of "Columbo" and "The Rockford Files") "The Streets of San Francisco" doesn't really hold up as well some 30 years later. While it certainly isn't bad, I see it more as a competent cop drama rather than a classic.
The ingredients are there - Karl Malden and Michael Douglas are terrific actors and they have the potential to make a great "odd couple" pairing. However, the pedestrian scripts don't give them a lot of room to work and there's nothing outstanding about the show. Crimes are regular stuff, and they tend to blend together. Malden and Douglas bicker and banter, but it never really feels genuine. It hurts even more, knowing that these actors are capable of better performances.
There's plenty of local color, and the show gets points for taking advantage of its locale. It's rare in TV today to see a show like "Streets" or "Hawaii 5-0" that makes its setting such a major part of the drama.
Don't misunderstand me - I don't think "Streets" is bad. I'd still take it over most of the prime-time dreck today. But I don't think its writing was strong enough to rank it up among the kings of 70s crime drama.