We didn’t really want to watch this, but we absolutely had to be part of the conversation. When people start maligning our much-loved comic book movies and thinking they can do it better, we need to get in there and see for ourselves. Joaquin Phoenix plays this (apparently) grittier, more realistic version of the Joker, directed by The Hangover’s Todd Phillips, trying to reinvent himself as an auteur. Did it deserve the top prize at Venice? We discuss.