Brian Eno's Music For Films was released in 1978. A compilation album of short, fragmentary instrumentals, it was pitched somewhere between conceptual and functional: some of the tracks did, in fact, end up in films, but Music For Films was also an exercise in soundtracking the cinema of the imagination, trying to synthesise imaginary, filmic moments and blur the divisions between sound and vision.

His new album, the first Eno release on Warp – the fact of which sets it up as some kind of brave new beginning – is something of a sequel to that album, and to More Music for Films (1983) and Music For Films Vol 3 (1988), with its short tracks, impersonal, cyclical melodies and mood-led sonics. It is, more literally, film music: Small Craft On a Milk Sea's genesis was as unused music for Peter Jackson's The Lovely Bones, reworked and jammed on by Eno and current choice collaborators Leo Abrahams and Jon Hopkins. So it is not a new idea, nor a new collaboration, nor a very new-sounding album, but Eno's music has always aimed at timelessness, at once new and not new, eschewing rock's linear narratives to swim around in numerous parallel nows.

It is not Eno's fault – although it's not been to his disadvantage either – that the 'soundtrack to an imaginary film' concept is now so commonplace that it no longer stands up as a concept, it's just a thing, a clump of words, no more meaningful than 'rock' or 'punk'. Nor is it his fault that he's now releasing this would-be conceptual mood music in 2010, into a hungry data-stream of sounds and images in which it can seem as if everything is functional, everything has its place and its reference points, and each sound has a visual analogue already. This multiplicity can be exciting, but take too much notice of it and it can also be enervating, flattened, dry like a guitar going straight into a Powerbook; choice can alchemise into blandness, as if everything has been compressed into one narrow bandwidth. Unfortunately, a fair bit of Small Craft inhabits that bandwidth.

Small Craft is not literally lacking in dynamics or diversity of instrumentation, but perhaps that's the problem - there is too much at Eno, Abrahams and Hopkins' fingertips for them to achieve that lovely, ominous and slightly clunky fragility you hear in Eno's best ambient works. The best tracks, 'Complex Heaven', ‘Slow Ice’, Old Moon' and 'Late Anthropocene', keep it murky and simple, hinting at things unheard and unseen and holding back overly smooth melodic gestures. In almost direct contrast to Small Craft's distant forebear, Music For Films, the fragmentary feel (most tracks are around three minutes long) is unsatisfyingly noticeable. On the 1978 album, the equally short tracks – most around the two-minute mark – drift and cluster like a phrases in a conversation, their brevity just part of a more detailed whole. Here, the best track is probably the longest, 'Late Anthropocene', because it feels the most committed and developed.

The middle, 'fast' section of the album has commanded some attention for its 'abrasive', rocking feel, but it is here that those compressed, flattened qualities really come to the fore. These tracks do indeed sound like film music – 'Horses' reminds me of the bit in a cyber-thriller where someone does some high-level hacking before running down some stairs really fast, while 'Flint March' and 'Paleosonic' summon stylish, CGI urban dystopias – but in the sense that, were it to come booming from the surround sound at your multiplex, you'd barely notice it. It's skilfully delivered – Hopkins is an experienced film soundtracker – but some film music only really works when you can watch a building blowing up at the same time.

Abrasiveness is a delicious quality, properly done. Here, and on 'Two Forms of Anger' most of all, the idea of abrasion is delivered with an unappealing good-manneredness, the airless, amp-less guitar interjecting little post-punk scrapes and squiggles at just the right intervals over a rumbling drum sequence and synth squelches. The track then breaks into a joyless, NME-friendly, bloke-motorik that's even more of a disappointment for being delivered by one of the few Krautrock contemporaries who really 'got' what kosmische music was about, who really dug its playfulness and strangeness.

Eno is cleverer than I am, and has made some of the most distinctive music of the last forty years; I've listened to and loved it for almost two decades myself, never tiring of it, often turning to it. So it baffles me that he picked 'Two Forms of Anger' to the be the album's trailer, releasing it two months ahead of the whole thing, given the better, less 'rock', tracks on the record. Perhaps he asked his collaborators what people were listening to at the moment; perhaps he had a chat with Rother about the success of Hallogallo 2010. Perhaps this is his reading of the current state of alternative rock music – that it's shallow, insular, obsessed with namedropping the past and getting things 'right' – and he's feeding it back to us, mischievously. As a fan, I might be making a leap of logic too far, but perhaps Small Craft on a Milk Sea is the Eno our generation deserves.