Just to be cool?
To me, for a movie to be good, it has to make me feel something. Love, hatred, disgust etc...
Dom Hemingway, as a character, didn't make me feel anything. There was nothing that made me feel for the character. He did not have a single trait which made him relatable.
Don't get me wrong, I am a big fan of antihero films and I really loved Filth (which people seem to compare with Dom Hemingway). But there was something in the way that McAvoy portrayed his character that spoke to me or, at least, that made me relate somehow (a humanity, real feelings).
In my opinion, the director wasn't successful in creating a connection with Dom or any of the other characters. The story was sloppy and I found myself not caring whether he rebuilt a relationship with his daughter. There is not a single episode throughout the film where I felt even a shred of sympathy for him.
It seemed like one of those movies that are just made to be cool. It reminded me a lot of Guy Ritchie films which are not to my liking (so you get where I'm coming from). There wasn't any real backbone to the story, apart from Jude Law there were no memorable performances (yes, while I did not like the film, Law is a good actor), and there were a lot of subplots which were left hanging (like how it's implied that Lestor would not go after Dom, really?).
It seemed like the director was too preoccupied with making the film look cool (fast editing, cocaine use, 'witty banter' between the characters) to give a real strong identity to the film.
If you disagree, fair enough! It would be interesting to know why, though.