The movie is about revenge, as you have guessed. More specifically about an armoured car robbery gone wrong. So what is new then? Well there is some obfuscation about the who is who in the greater scheme of things. Unfortunately that is not enough to make this more than a run of the mill revenge story of the classical type: Man gets wronged, man gets revenge.
It is a movie full of potential, but lacking in delivery. It builds your hopes up multiple times expecting something great, then it always under delivers on its own promises.
One issue with the movie is that it has no character development to speak of, everyone is stagnant, they don't go from A to B. And there is token female security guard who has every trope in the book, including the idiotic notion that a woman has to act like a man to do a "man's" job. It is as sexist a depiction as it gets.
I'm so sick and tired of this, why can't a strong female character remain girly or god forbid sexy?
But by far the main issue with the movie is the ending where almost everyone gets killed off unceremoniously without reason or reward. There are no redemption arcs or heroic moments, only worthless and pointless deaths.
The story itself stands on rickety legs and requires extraordinary amounts of suspension of disbelief to not zone out of it. There are too many things that doesn't make any sense if you think about it for just one second. Like for example the same armoured car company getting robbed almost weekly. Or why the FBI is happy to look the other way. The setup of the initial conflict is so contrived that it makes you mad.
The movie is advertised as Guy Ritchie's darkest yet, but the only reason it can be called dark is because of the pointless deaths. Otherwise this is far less dark, witty, and entertaining, than either Snatch or Lock Stock and Two Smoking Barrels. It cannot hold a candle to either of those classics.
It's not bad, but this is not what a good movie looks like: 5/10