Last summer, Daft Punk's soundtrack to Tron: Legacy leaked on the internet. You would think that Daft Punk fans might exercise caution when it comes to internet leaks after that unfortunate business with their last studio album, 2005's Human After All. When tracks purporting to be from the follow-up to the multimillion-selling Discovery emerged online, a lot of devotees rushed to announce that they were very obviously faked, that two zeitgeist-defining musical geniuses such as Thomas Bangalter and Guy-Manuel de Homem-Christo couldn't possibly be responsible for anything so shoddy and uninspired. In the enormously unlikely event that they were responsible, it was suggested, these tracks were clearly intended as a joke to put people off the scent of their forthcoming masterpiece.

Unfortunately, the devotees duly discovered that no, they weren't faked; yes, Bangalter and De Homem-Chrosto were responsible; and no, the tracks weren't a joke. This time, the Tron leaks turned up everywhere – just in time for Disney to announce they were not the work of Daft Punk at all, but a slightly nutty-sounding Daft Punk fan with a YouTube account.

At least it told you something about the degree of anticipation for the soundtrack. There's being excited about a forthcoming record, then there's being so excited that you start speculating wildly about what it might contain, then there's being so excited you come over all Mike Yarwood and start doing impersonations. You can see where the expectation comes from, though. For one thing, Daft Punk might have been put on Earth specifically in order to record a soundtrack for a sequel to Tron: their 80s retro-futurist aesthetic is clearly indebted to the original, which variously features primitive electronic graphics, the soft rock of Journey, a plot in which a programmer becomes part of a neon-glowing computer mainframe after being shot with a laser, and the Scarecrow from Scarecrow and Mrs King. It occasionally seems less like a film that actually got made than a dream Thomas Bangalter might once have had.

Second, Daft Punk's ability to shift the course of pop music has been proven beyond measure. The filtered house of their debut album Homework spawned imitations from everyone up to and including Madonna. On its arrival, Discovery appeared to be a cheese so ripe it threatened to stink your house out. But, for better or worse, it turned out to presage virtually every subsequent development in pop for the next decade, from the prevalence of Auto-Tuned vocals to the fetishisation of the 80s to the rise of the Guilty Pleasures phenomenon: it may well be the single most influential album of the last 10 years. What effect might the duo have on the world of the film soundtrack?

The faked tracks just sounded like Daft Punk, which apparently was never on the cards for the actual album: "We knew from the start that we were never going to do this film score with two synthesisers and a drum machine," explained Bangalter of their decision to co-opt an orchestra. The results fall more or less into three categories. There are the straightforward orchestral tracks, which sound suitably grandiose and cinematic, but with the best will in the world, could be the work of anybody. Then there are the tracks that attempt to meld electronics – usually a lonely throbbing synth line – with sawing strings and brass sections. These have some lovely moments – Rinzler's dramatic explosions of In the Air Tonight drums, the beautiful ebb and flow of Solar Saile – but there's something faintly underwhelming about them, perhaps because the inspiration of 80s-era Maurice Jarre and Vangelis hangs heavy over them, and dance music has explored both those influences pretty thoroughly in recent years. Anyone with an inclination towards the kind of 12‑in singles that get bracketed as cosmic disco or new Balearic will undoubtedly have heard stuff that sounds like this. It won't necessarily have been better, but there's none of the head-turning WTF? factor that's accompanied past Daft Punk tracks in the past.

That leaves us with a handful of straightforward electronic tracks. You almost feel bad for saying they're the best things here, given that Bangalter and De Homem-Christo have gone to the extreme of employing an 85-piece orchestra in order to not make straightforward electronic tracks. But there's no getting around the fact that Tron: Legacy gets really exciting when there's no one but Daft Punk in the studio: the corroded synthesisers and overloaded beats of Derezzed; the insouciant strut of End of Line, with its addictive, repetitious melody; the two minutes of Fragile, which – at risk of sounding desperately callow – sounds like the intro to an amazing dance track.

It might all work brilliantly in the cinema, allied to Tron: Legacy's 3D visuals. If it does, it wouldn't be the first Daft Punk album to be reconsidered over time: people certainly revised their opinion of Human After All after seeing its tracks performed live. For now, however, it's hard not to feel a bit disappointed. As is so often the case with sci-fi, the future hasn't turned out quite as you might have hoped.