This film has a fairly unoriginal premise: cop guy still suffering the death of his family goes out for revenge. The particulars of the crime plot - drugs, money laundering, and other organized crime activity - are also nothing to get worked up about. It's not that they're done badly or even cheesy, but they have all been done before.
What makes this film worth watching is the lead character and the actor who plays him. Willie Serling, played by the wonderful Anthony LaPaglia, drifts in and out of so many false personalities as part of his undercover operations that he's not sure who he is himself anymore. Not only does LaPaglia adeptly handle character changes - moving in and out of accents, mannerisms, gaits, etc. - but he also really brings home the performance of Serling struggling to keep a grip on his own life. LaPaglia's performance is so good that it's easy to forget about the plot issue. Furthermore, the character himself is interesting to watch as he navigates the story.
So don't watch this movie if you're looking for the best crime drama ever, but definitely watch it if you want to see a genius of an actor at work in a thoroughly interesting role.
If you're a fan of movie makeup, that part of this movie alone should entice you. Fabulous work by the makeup crew makes for a fun Spot-The-Agent game on the part of Willie's boss. If the crew didn't get an award for their work, they were robbed.