The important thing to know about writer-director Sean Baker's new movie isn't that it was shot entirely on an iPhone, or that it's the buzziest tale of transgender prostitute revenge you're likely to encounter on a screen this year. Those things are true, but what's important about Tangerine is that it's so cathartically hilarious. It's at once a triumphant return to indie-film first principles — rawness, resourcefulness, sheer delight to be doing it at all — and a hot strong breath of fresh air.