The star-power is bright: Sean Penn, Josh Brolin, Ryan Gosling, Emma Stone, Giovanni Robisi, Nick Nolte and a few others, but none is especially outstanding and Emma Stone--whom I have adored most of the time--is decidedly miscast as a mobster's mall. She's not in the same universe with her character. Penn's over the top; Brolin is wasted and Gosling, Robisi and Nolte are close enough to get about half a cigar among them.
This is a movie that opens with a rival gang member being chained to the bumpers of two cars and pulled apart. The violence grows from there, even though one of the big gun scenes in Grauman's Chinese Theater was eliminated in the wake of the murders of children in Connecticut a few weeks ago.
At the center of "Gangster Squad" is the downfall of Mickey Cohen, a ruthless and notorious 1940s West Coast gangster. The L.A. cops--mostly corrupt at the top--have to rely on a small group put together to stop Cohen and these guys have to break the same laws Cohen's breaking in order to be effective.
The moral dilemma is the same one we've seen over and over (should we spit on the Constitution in order to take down really, really bad people? In this movie, the answer is a decided "yes!").
Truth: I kind of enjoyed this flick. OK, guilty pleasure by a professed pacifist. No, I can't 'splain it, Lucy and dang if I can fight it. I keep showing up at these movies with far more gunfire than is comfortable and I keep not loving them, but liking a lot of them--to my dismay. You're on your own here. I can't make a recommendation either way.