Gangster squad is set in late 1940s Los Angeles, with the city under the control of real life gangster Mickey Cohen. Hotheaded but honest cop John O'Mara, played by Josh Brolin, is chosen to put together a squad off the books to wage guerrilla warfare against the 'enemy occupation' of drug runners, whorehouse overseers and tommy gun toting gangsters that wear the badge of Mickey Cohen.
This true story is exaggerated into life on the big screen with stylish flair. Fast forward and slo-mo is liberally applied to the competent action beats to give them a glossy sheen. Ryan Gosling and Emma Stone provide the sex appeal as the sexy cop and sexy femme fatale (although unlike real femme fatales, Stone's character is a good girl pretending to be bad). O'Mara and his wife give moral grounding and warm fuzziness. Giovanni Ribisi plays the gang's tech expert and sympathetic family man (after O'Mara), while Max Kennard plays the gunslinging bad-ass and Michael Peña his junior partner and part time comic relief. There's also a black guy who's good with knives, because every team needs a black guy and someone who uses knives. So I guess they saved money by rolling them into one? Anyway, he's played by Anthony Mackie and he's pretty bad-ass as well.
Pretty much all the actors do well with their parts. The chemistry between Gosling and Stone isn't great (I've heard they had another film together where they shone, but that's not evident here), but it serves its purpose. Everybody plays it up and creates a fun atmosphere at the times when the film hits its stride; there are some good montages and exciting action moments. Sean Penn plays Mickey Coen, and while he's nothing like the real life gangster, he's over-the-top and fun to watch. He gets a couple of monologues declaring himself 'God' and 'progress', and the crazy really comes out in these moments, it's all good fun.
But sometimes the film seems to be wanting to be taken seriously. Apart from the executions, which are gratuitous but forgivable, there is also a scene where Ribisi's character wonders who the real monsters are; 'What separates us from them?'. The scene feels slapped on, shoddily done, and it also rings hollow because we've just seen a montage of the gangster squad doing their thing - doing horrible violent things to the bad guys for sure, but also burning money, saving captured women and disrupting the influence of crooks on the city. They may have done some bad things, but there's a clear line between them and the villains. Most would agree that what they've been doing is for the greater good. There are elements of the film that are unexpected - even refreshing - but cramming this cliché in there (amongst others) doesn't do it a lick of good.
Other than that... not much to say. There's a boxing scene. It's alright. There's a car chase. It's alright. It's a fine film if you want a bit of violent fun and a few good laughs, but nothing about it reaches the level of exceptional.