This is one of the least fun movies you will ever see, but it is very good. It belongs to the particular subgenre of British cinema known as "kitchen sink drama": gritty, unglamorous portraits of the lives and problems of working-class Brits. I haven't seen as many of these movies as I would like to, but this one is surely among the grittiest and least glamorous of the bunch. There's not much to smile about here, but the movie works quite well, I think.
The movie follows Joseph (Peter Mullan), a man with serious problems about alcohol and rage. One day, on the run after starting a fight in a bar, Joseph ducks into a shop run by a kindly Christian woman named Hannah (Olivia Colman), and they begin a very tentative sort of friendship. If that premise sounds potentially sentimental, I assure you it's not - Hannah doesn't work any miraculous changes in Joseph, and indeed it turns out that she has very serious problems of her own. The movie is basically a catalog of pain.
This is one of those movies that leans very heavily on its actors, and luckily they're both extremely good. Mullan is utterly convincing as Joseph - we see the constant rage, but Mullan makes Joseph human and somehow sympathetic anyway. Olivia Colman here is, to use a cliche, a revelation. I had seen her before on a couple of goofy British comedy TV shows - That Mitchell and Webb Look and Peep Show - and had no idea she had this kind of performance in her. It's a complete 180 from her previous work, and shows she has depths I had never imagined. Eddie Marsan, whom you might know as Lestrade from Guy Ritchie's Sherlock Holmes movies, also appears as Hannah's vile, abusive husband. This is the type of role an actor takes when he doesn't care about his image. We never get much insight into that character, but then again we don't really want to.
At times, the movie might veer a little close to the Precious problem of just throwing too many horrors and catastrophes at its characters, but I think it ultimately dodges that. The look of the film is consistently gray and dour, reflecting both the English weather and the characters' constant depression. It was the first film written and directed by the actor Paddy Considine, but it feels very confident in its approach. If you go to movies only for escapism, then avoid this one; but if you like this sort of hard-hitting, hard-to-watch drama, then I recommend it.