I just saw a preview of 'The Disaster Artist' which is about the making of 'The Room' (or 'the best bad movie ever made'). It was unexpectedly moving! A really charming film about friendship and following your dreams. It's also hilarious. James Franco is fantastic in it.
I'd also recommend seeing 'The Room' first to truly appreciate 'The Disaster Artist', but it is a truly dreadful film (with some unintentionally hilarious moments).