Over the years, cinema has brought us some pretty unconventional relationships: a teen and an OAP (Harold and Maude), a girl and an oversized gorilla (King Kong), a beauty and a beast (er, Beauty and the Beast), and a girl, a vampire and a werewolf (Twilight) to name but a few. Director Spike Jonze, who has a knack for the curiously sublime, does it again with what has to be a first in terms of romantic pairings – a man and an operating system.

It's been almost a year since Theodore (Joaquin Phoenix) broke up with his wife, and in that time he's struggled to get back into the dating game. It doesn't help when he spends most of the time either at work (as a writer of letters for a website called Beautiful Handwritten Letters) or at home playing video games.

When he bumps into his friends, who are a couple, living in the same block as his, he's reminded of how nice it would be to be in a relationship. So he tries dating again, but it doesn't quite work out.

He then installs a new operating system onto his home computer; a completely unique software experience that brings with it an unparalleled level of artificial intelligence. Not long after its initial boot-up, the OS1 names itself Samantha (Scarlett Johansson). It's not long before Theodore understands just how impressive the AI is, so much so that he soon realises that he's not only developed a bond with Samantha, but also a romantic relationship. They say that true love can overcome any obstacle, but does this compute for Theodore and Samantha?

I'm sorry, but that font is just plain offensive, I simply can't look at it.

One of the most disappointing aspects regarding Spike Jonze is his sporadic bouts as a director. Her is only his fourth film since his debut with Being John Malkovich in 1999, which is just a crying shame considering his formidable talent. And although Her isn't his best work, it's still an intriguing tale.

Although we can already develop relationships one way or another with the technology available to us today – Apple's chatty Siri for instance, who's more than happy to let you know if you will need a brolly for the day or not - Jonze sets his story, which he also wrote, in the not so distant future. It is an allegory for the loneliness that the advances in technology can create, despite the irony in terms such as social media; despite living in a metropolitan area, the only relationship that Theodore can commit to, is one with a voice created by his computer. It sounds human, reacts and behaves like a (female) human, but is no more flesh and bone than a toaster.

It's a concept that resonates with elements of our relationship with current technology, yet it's its execution that is somewhat of a turn off. For the majority of the film Phoenix is pretty much talking to himself on camera. He does well considering, after all most actors in this day and age of CGI are used to playing opposite a sock or tennis ball floating in the air against a green screen, which will be turned into something animated at a later date. For the audience however, despite a tight and compelling script, visually watching Phoenix pretty much talk to himself for two hours soon loses its appeal. There's no denying an emotional connection, but it's one that's difficult to hold your attention for any length of time; it's kind of ironic really, when you consider that technology itself is responsible for reducing attention spans to milliseconds (if you're lucky) as it is, thanks to this app or another.

Jonze may not have made many feature length films to date, but he continues to direct music videos and short films. This is a project that would have been better suited to either one of these mediums, with the kind of concept that wouldn't rattle around within a shorter time frame. As it stands, Her's story of a man in love with an operating system may well be strangely logical, it just doesn't have any sparks, virtual or otherwise, to make it last in your memory.