We've grown fond of the characters, which saves the film a bit - on its own, without the backstory, it'd be much less effective. If anything, it's at least a relatively enjoyable experience that you can palate for a short time. Think of it as going down easy in small doses, like eggnog.
In his opening remarks to "Andy Warhol: Motion Pictures," MoMA's Chief Curator at Large Klaus Biesenbach told us to think of Warhol's screen tests -- 12 of which are presented in large-scale on the wall of one gallery -- as portraits.
Only the very young and the very undiscriminating will find this movie enchanting -- or even mildly entertaining. Obviously, Jackie Chan isn't immune to making one for the paycheck and phoning in his performance.