I liked it but I saw it as a celebration of how the NRA became powerful and how they keep winning. I'm sure if you wanted to see it as a hit piece you could but I did not. Watching gun control advocates whine about losing kind of makes me smile. If you missed the show it is also posted online.
http://www.pbs.org/wgbh/pages/frontline/gunned-down/
http://www.pbs.org/wgbh/pages/frontline/gunned-down/