A question stalking Kevin Macdonald's study of Whitney Houston is whether it does enough things differently to justify a release so soon after Nick Broomfield's excellent Whitney Houston: Can I Be Me.

Well, we don’t get much fresh analysis of the music. It is a smaller aspect of the Houston tragedy that, for all her success and for all the majesty of her voice – scarcely human in the precision of its louder notes – those records are still condemned to the Kingdom of Kitsch.

Whitney Houston never calculated as coolly as her near-contemporary Madonna. The socio-political brilliance of later Beyoncé could hardly be more remote from the wedding balladry of Saving All my Love for You. In Macdonald's film, we see Whitney receiving boos at the Soul Train Awards for, it is assumed, the crime of being too vanilla for the post-hip hop era. These records still require a little more respect.

Back to the sorry decline from sparkling prodigy to delicate idol to doomed cocaine addict. The new film does have at least one shocking revelation to set itself apart from Can I be Me: the suggestion that Dee Dee Warwick, cousin to Whitney and sister of Dionne, molested the singer when she was a girl.

It is ambiguously argued here that that experience may have so troubled Whitney as to make her doubt her own sexuality. It's not clear if the speaker is suggesting she was driven away from men or towards them. But Whitney's lengthy relationship with Robyn Crawford – whose voice is conspicuously absent here – seems to have been more stable than that with any male lover.

For all the pre-release revelations, the story about Dee Dee takes up only a small part of Macdonald’s film. What sets it apart from Broomfield’s film is more a question of style.

Whereas Can I Be Me was gritty, nervy and idiosyncratic, the current film is as slick, professional and mainstream as Macdonald's breakthrough One Day in September. The talking heads are all shot in clean, pretty light. The film moves smoothly and chronologically through the life. It ends with a belter from the star.

None of this is intended as negative criticism. Macdonald is a skilled film-maker and a perceptive interviewer. He has somehow managed to get Bobby Brown, to whom Whitney was married for 14 years, into the film and, when the singer wriggles out of questions about drugs, Macdonald calls him out in a clean, posh Scottish accent.

Whitney has less political sweep than Macdonald's film on Bob Marley, but, at such points, you are reminded there are even rougher emotions at work. Blame is slung in one direction. It is then batted back in another. At times, one feels like an observer at a more than usually awkward wake.

That story about Dee Dee Warwick aside, the film does not offer many new angles on a too-familiar story of how fame can eat a fragile sensibility. What it does offer is much moving testimony.

Whitney’s aunt breaking up as she remembers the star’s doomed daughter Bobbi Christina Brown is as heart-wrenching as anything you’ll see on screen this year.

For all its gripping accumulation of second-hand miseries, however, Macdonald’s film fails to give us enough of Whitney Houston herself. There are surprisingly few clips of the star telling her own stories. There is almost no attempt to understand why the music registered with so many people in so many countries.

Whitney will be filed under "music documentaries" but it is no more about music than it is about carpentry or mathematics. The tragedy is so blistering that – as it would be if shooting into the sun – it blasts everything else into bleached insignificance. Maybe that's how things should be.

Opens: July 6th