Wicked boring movie
The acting was good, the realism was good, I liked the cars of the era, and I liked the "look" of the film (i.e., typical 1970s 35mm film stock), but the plot was dull as a lima bean.
There were no interesting cases that Serpico or anyone else was working on, and there wasn't even a plot to kill Serpico. They were all basically just highly annoyed with him, and a few of them issued some vague threats, and the worst anyone did was pull a knife on him (as another threat of course, no actual intention of attacking him with it). If you want to speculate that cops set him up to get shot at the end, go ahead, but there is nothing in the movie that establishes any such thing.
On top of that, the dirty cops that he was so hell-bent on bringing down weren't even doing anything outrageous (at least not by movie standards), like raping or murdering. Instead, they were "on the take".
Based on the opening, I assumed that the movie would have a plot about dirty cops plotting and eventually carrying out a "hit" on the "rat" cop. If that had been the plot, combined with an interesting crime case as a subplot, it could have been a good movie.
Oh yeah, and there was some "relationship drama". He wouldn't marry the first woman, so she casually left to marry someone else. He wouldn't marry the second woman either, plus he hollered at her a few times and she didn't like that, so she left too. Gee.
And the movie was entirely too long for a story that makes for a good newspaper article, but not much else.
I don't dance, tell jokes or wear my pants too tight, but I do know about a thousand songs.