Sometimes in video games or animation there will be poor dubber who phones it in, they sound very lazy or are probably just in the bathroom reading some paper. It's a truly rare case where an actor of a movie does this, the leading role even, in a perfectly soulless manner. The lead Danny Dyer just stands there muttering some lines with the expression range of one who suffers Botox overdose. Other theories include unworldly possession or he might just be a robot, that would be far more fascinating.
Jamie (Danny Dyer) is a poker-faced hit-man. One day he meets with a woman who turns out to be involved with his work. There is little acting to speak of, some supporting characters are decent, but almost the entirety of the movie is spent on looking at Jamie looking at nothing. He looks the same when he kills people, engages in small talk or meets the love of his life. Audiences at home are probably more vivid as they react to the unbearable stiff acting.
Visual is bizarre, the camera seems to be shifting from side to side for no reason. It would shuffle slightly to the back of the head when normal conversations occur or wobble from behind some object. There's also plenty of running or riding bike, which is fine to create atmosphere, but it feels unnecessary after the twelfth time. The script is so abrupt and random, it doesn't even explain basic plot clearly let alone convince the audiences that it has authentic relationship.
Soundtrack is a repetitive humming theme throughout the movie, and at times it blasts the volume for screaming scenes. People, especially girl characters, would scream so zealously in hope to prevent audience from sleeping through. Action is nearly non-existent. Forget about choreography, Assassin only stands there, equally rigid, and fires away. No stunts or believable motion like taking cover.
There is no aspect of this movie that isn't severely flawed. Beware, Assassin will kill your time. That pun is as cringe-worthy as the movie.