The reasons why this film isn't a patch on its predecessor – In Bruges – are many, but the real root of the problem is that there is no reason why we should care about anything or anyone in the film. It's so self-referential that it disappears up its own meta text. To understand why it fails, you have to look at two other films.
One of them, obviously, is In Bruges, which Martin McDonagh wrote and directed in 2008, and which is in every way superior to this. The core narrative of In Bruges is the relationship between Colin Farrell and Brendan Gleeson, two Irish hitmen exiled to Bruges after a job has gone wrong. The first hour of the film is a masterpiece of writing, as we see the two men bicker while they wander through the city, creating a funny and intriguing friendship.
Nothing of the sort is available in Seeven Psychopaths. Colin Farrell reappears but this time he's a scriptwriter called Martin with drinking problems and writer's block. He has the title for a film (7 Psychopaths) but no idea what to do with it. He has a best friend, Sam Rockwell, who runs a dognapping business with Christopher Walken, but Rockwell is merely a stereotypically goofball guy who turns out to have a dark side, just as Martin/Farrell is a stereotypically confused writer lost in translation. Nearly all the other characters either make brief cameo appearances, only exist in Martin's imagination, or continue in the stereotype mould – Woody Harrelson's gangster, for example.
Which leads us to comparison number two. The best film about a writer having problems with working is Adaptation, Charlie Kauffman's wonderful film starring Nicolas Cage as Kauffman himself and Kauffman's non-existent twin brother Donald. The script is witty, insightful, and presents a portrait of the fictional Kauffman as a fucked up and insecure guy, whose ways of dealing with his anxieties are all too human, and often very funny. Although the film flits in and out of different sorts of reality, we always know where we are and why we're there because Kauffman has done the work. I'm not sure the same can be said of McDonagh's script. It's simply a bunch of ideas which he's chucked at the screen, in the hope that some of them will work. And while a few of the scenes are enjoyable, as a whole the film is empty and frustrating.
It amazes me that people have still not grasped the need for audiences to care about characters and what happens to them. There are numerous deaths in the film, including several of the main characters, but you don't give a hoot, because you have no emotional investment in their existence or their lives, and so you neither believe nor care about what happens to them. The whole project is untethered to any kind of reality, which is another profound mistake. However fantastical the premise (like Groundhog Day, for example), a film has to have its own rules and abide by them. Seven Psychopaths simply makes it up as it goes along, leaning on the tired excuse that it's all a film within a film within a film. Bollocks.
I've seen a lot of much worse films in my time, but there is a waste of resources here, as well as a big letdown after the brilliance of the previous film. Let's hope lessons are learned, because this is a dead end with few redeeming features.