It’s difficult to categorize “Jackie,” Pablo Larrain’s artsy film about Jacqueline Kennedy. On the one hand it’s a sort of psychological portrait of the First Lady in her darkest days, immediately following the assassination of her husband. As such it’s a rumination on grief in a more general sense. It’s also a study in celebrity and myth-making, as Jackie is shown effectively creating the “Camelot” motif for JFK’s brief presidency, as well as staging his elaborately theatrical funeral ceremony in the face of political pushback from the new administration. And, finally, it’s a simple star vehicle for Natalie Portman, who’s called upon to channel a familiar figure and pulls off the task with a proficiency that will certainly attract the attention of those who hand out acting awards at this time of year. Whether all of this amounts to much more than a bit of tabloidism with pretensions, however, is open to question.

The wraparound plot thread involves the first post-assassination interview Jackie gives to a deferential journalist (Billy Crudup). Flinty and domineering, she reveals a good deal about her attitudes but makes it clear that she will control what the reporter will be allowed to print. That leads into fragmentary shards of memory, sometimes historical reconstructions (like a surprisingly graphic reenactment of the moment at which the bullet struck the president’s skull) but more often speculative musings on her state of mind (such as a sequence in which she rambles through the White House in a haze). A major theme is that of transition, with the Johnsons (John Carroll Lynch and Beth Grant) portrayed as rather insensitive interlopers and Jack Valenti (Max Casella), LBJ’s aide, as a minion trying to squelch Jackie’s plans for a funeral procession that would include an array of dignitaries walking along with the casket. A haggard Robert Kennedy (Peter Sarsgaard) is also at the forefront in these scenes, acting to protect his brother’s memory while supporting his widow.

Other elements of the mosaic smoothly confected by Larrain with the aid of cinematographer Stephane Fontaine and editor Sebastian Sepulveda, include a partial recreation of the 1962 TV special, “A Tour of the White House,” combining black-and-white facsimiles of bits from the program with color scenes of Jackie being simultaneously reassured by her aide Nancy Tuckermann (Greta Gerwig), an impressionistic view of a recital by cellist Pablo Casals at the residence, and a confessional conversation Jackie has with the priest (John Hurt) who will officiate at the Arlington burial, in which she bluntly admits the low points of her marriage and questions her own behavior then and now. There’s also a particularly touching scene when she must finally try to explain to her children that their father won’t be coming home again. And repeatedly the film returns to what amounts to a face-off between Jackie and Crudup’s journalist, whose every probing question she meets with dismissal or a sharp reply.

Throughout Portman invests both the private and the public Jackies with vulnerability as well as steeliness. It is, however, inevitably a turn that brings a good deal of imitativeness to the fore, like an acting exercise that one can’t help but admire for its technique even as you might be put off by how mannered it is. The same observation applies to the film as a whole: Larrain has never been a particularly straightforward director, but here he exploits every device he can to give fluidity to the succession of images and emotions jammed into Noah Oppenheim’s script. And the visuals are overlaid with the mournful strains of Mica Levi’s score, which often mimics moaning and might just drive you to distraction. Nevertheless, the main members of the supporting cast—Sarsgaard and Gerwig in particular—register strongly despite the dominance of Portman, although Crudup and Hurt underplay so much in her presence that they become nearly anonymous.

It’s difficult not to be ambivalent about “Jackie.” On the one hand it’s an artistically accomplished portrait of the woman as a complex personality caught at a moment of terrible personal loss. On the other it’s a highly speculative piece that can come across as more than a little crass, even tawdry. As such it’s probably a perfect fit for an age that seems to presume that when it comes to the private lives of the powerful, discretion and decorum no longer have a place, and the public have a right to know every detail about them, however embarrassing—indeed, especially if it’s embarrassing. Of course it no longer matters whether the information doled out is true, and in that respect Larrain’s film might be just about as accurate about Jackie as Oliver Stone’s was about her husband. But as with “JFK,” many people might take “Jackie” as the way it really was. That’s what makes the film so powerful—and so troubling, perhaps even dangerous, from a historian’s perspective.