Perhaps you would think, from the advertisements (which play up its ties to Little Miss Sunshine), from the presence of Alan Arkin (playing almost exactly the same character he played in Little Miss Sunshine), from the subject matter (the ways that family members both love and hate each other, and the crazy ways they prove it, as in Little Miss Sunshine), and from the word "Sunshine" in its title, that Sunshine Cleaning is a quirkilicious drama-comedy built from leftover parts in the Sundance Labs supply room with an eye to exactly replicating Little Miss Sunshine. Lord knows I did. And it turns out that I wasn't right.

In fact, Sunshine Cleaning would probably benefit from being a bit more slavishly similar to the 2006 Oscar-winning indie, in at least one respect. See, it's not yet another of those apparently mass-produced quirky independent dramadies that we have here, it's a quirky independent drama, with a cheerful attitude and just enough gags to put together a misleading trailer. But it's not really a comedy in any useful sense, by which I mean it's not all that funny. Most of the time, it's honestly a wee bit depressing. And this is where things fall apart. The whole quirky indie movement - "quirkycore", I have decided in this moment I shall call it - certainly does not eschew drama, but for the most part every film in the style - Little Miss Sunshine and Juno are the biggies, but there are plenty of others - has ultimately been primarily funny, and only secondarily about human conflict. Sunshine Cleaning is all about the psychic trauma felt by two sisters, single mother Rose (Amy Adams) and Norah (Emily Blunt), and how they both achieve catharsis through Rose's wonderful business idea, to horn in on the lucrative world of death-scene housecleaning.

"Quirky" "cathartic" and "psychic trauma" turn out to be a poorly-matched set. What is charming or annoying in various degrees in the many films that Sunshine Cleaning copies is flat-out bad here; the film always works at cross-purposes to itself. The tone is too fakey warm and genial to give the dramatic content of the scenes any real heft, and in the end the whole damn thing runs aground on that central flaw. It's likely, I guess, that the filmmakers - first-time screenwriter Megan Holley, and director Christine Jeffs - don't even realise that they've got this problem; I'd imagine that they only ever wanted to make a sweetly bittersweet comedy, and failed to notice that the central conflicts of the film are brutal and borderline tragic.

Moving beyond that major, overwhelming flaw, the rest of the film is kind of messy in a lot of stupid ways. At times, I honestly wanted to blame the editing for getting everything mixed up, though in general there's nothing else wrong with the way the film is cut together, so I can only assume that the problems started with the script. At one point, for example, the sisters and their dad Joe (the aforementioned Arkin) are looking to buy a car for the business, and are directed to an old Econoline van; it is only while looking at the vehicle that they see fit to tell the seller what they're looking for. That's probably not severe enough to be a continuity error, but if you the writer are going to go to the trouble of having a character unnecessarily mention that she needs plenty of space in the back for hauling, why not put it before she's staring into the back of a van that, lo and behold, has plenty of space for hauling? Tiny little moments like that are all over the place, in really frustrating ways. Nobody in the film ever calls to make plans ahead of time, for a start. And we keep learning pertinent information in not quite the order that would make the most sense.

Add to that a few subplots and scenes that go nowhere and do nothing, although their apparent point is to show the tragedies that follow the sisters like magpies, and it's hard to avoid concluding that the people responsible for shaping Sunshine Cleaning into a narrative aren't wholly clear on the concept of narrative. "Things happen and then they learn something" isn't really a story, and having a whimsical conceit like the whole "clean up death scenes" thing can't paper over the fact that there's no progression from point to point. It is a flimsy construct made of recycled parts, and it's neither interesting nor entertaining nor meaningful as a result.

Now it's for the "Yes, but..." part of the review. Sunshine Cleaning is at best an indifferent screenplay executed lazily and sloppily, but the film is still at least kind of watchable. For a start, it has some unusually pleasing cinematography, courtesy of John Toon. I say "cinematography" although it's plainly digital intermediate, but the film has a slightly washed appearance that skews towards the yellow end of things, and Toon isn't afraid to underlight when underlighting is the right thing to do. I'm not used to films like this that are willing to keep away from the finished glossiness of a big studio film but don't fall into the trap of raw ugliness that so many independent films enjoy.

The normal people out there are much likelier to respond to the surpassingly fine performances of Amy Adams and Emily Blunt, two actresses that I've enjoyed for a good long while, both at the top of their respective games. Adams in particular is doing something similar to the chirpy doe-eyed optimist she always does, but with enough bitterness, sexuality and nihilism that performance doesn't feel like she's phoning it in. Blunt, meanwhile, is the same chameleon that she always is; hardly any actresses of her generation evaporate into every role so much that it's hard to remember who's performing, but that's a skill that Blunt has showcased every single time I've watched her. Between them, the two actresses suggest a whole vista of human emotion that the muddled script just kind of gestures towards in a vague way; it's not enough to save Sunshine Cleaning, but it is, maybe, enough that you can see the point they were all driving at.