“Why can’t I be Frank?”

That’s the question that comes to hang over milquetoast, mediocre keyboard player Jon (Domhnall Gleeson), just as the sullen mannequin-fucker Don (Scoot McNairy) predicted it would. The Frank in question is played by Michael Fassbender, though you’ll have to take my word for this, as he spends the majority of the film encased in a papier-mâché head, combining a unique (arguably insane) perspective on the world with impressive, idiosyncratic musical talent.

A similar question has hung over me in the week since seeing this film: “Why don’t I like Frank?”

I feel like I should like the film. It’s got Michael Fassbender and Maggie Gyllenhaal and quirky indie post-rock and quirky humour and quirky drama and just, really, a whole lot of quirk. It has all these ideas and themes coursing through its screenplay, asking questions like – what is talent, and why is it so elusive for some and so easy for others? Where does “weirdness” stop being weirdness and shift into mental illness? Where can we draw the line between selling out and inviting popular appreciation?

Frank lacks the glaring flaws that would explain my ambivalence. The cinematography is fine. The performances – particularly from Fassbender and Gyllenhaal – range from adequate to good, even if they’re generally working within character sketches than believable humans. I’ve seen a few critics complain about the film’s gloomy-bordering-on-tragic last act, either because the film isn’t delivering on the comedy promised in its misleadingly upbeat marketing or because they found the tonal shift jarring and clumsy. I can see the point, but I’m not entirely on board with this complaint; in fact, one of the things I really like about Frank is the way it earns laughs from its character’s “wacky” behaviour then subtly interrogates its audience, questioning whether we should be laughing at potentially mentally ill folks.

The problem with Frank isn’t its tonal inconsistencies – its darker tendencies are firmly embedded in its earlier grasps at comedy – but its thematic and narrative inconsistencies. The final act sees Frank’s (unpronounceable) band, Soronprfbs, travel to South by Southwest after Jon’s online posts, tweets and videos go – well, viral, perhaps, but only on the level of a mild cold. Anxious over the obliqueness of their sound, Jon pressures Frank into making more “likeable” music, which allows the film to address themes of artistic compromise and accessibility.

This is all well and good, but it lacks any narrative foundation. The majority of the film is spent in a flabby second act where Sornoprfbs abscond to a remote farmhouse to produce their debut album, where surely there existed an opportunity to establish Jon as a commercially-minded individual or, at the very least, substantially develop characters other than Jon. Without this, the simplicity of the final act feels disappointingly reductive, narrowing expansive themes down to a conventional conclusion about pop music, integrity and originality.

Jon is a boring character, a kind of modern day equivalent of Salieri, defined by mediocrity and a total lack of insight. This isn’t necessarily a problem! I think the choice to surround a group of weird people with an achingly ordinary guy is a potentially interesting choice. The film’s final scene, a heartfelt, weird and surprisingly touching musical performance, makes it clear that the filmmakers (director Lenny Abrahamson alongside screenwriters Jon Ronson and Peter Straughan) don’t have a great deal of sympathy for their unlikable protagonist. Unfortunately, the scene feels grafted in from a better film, a film that truly earns the emotion it strives for, a film that establishes its characters other than Jon beyond the surface-level.

If I had to answer my own question, if I had to make a decision as to why I didn’t like – or, at least, didn’t love – Frank, then it comes down to one thing. The film is too neat. For all its feints at quirkiness and originality, it resolves with a pat conclusion that brushes away its most potentially interesting ideas. Ultimately, Frank is too little like Frank, and too much like Jon.