Political junkies who lose the MSNBC feed on their cables will appreciate Oliver Stone’s “W.,” his third presidential epic but the first to take aim at its subject before he’s left office. They’ll find the movie, which shuffles back and forth in time to offer scenes from as far back as Dubya’s college days and as recent as the post-invasion debacle in Iraq, an intriguing collection of moments, some poignant but most of them barbed. What they won’t find—nor will anyone else—is much insight or revelation. Neither satire nor drama but a sort of stream-of-consciousness rumination on Bush past and present, Stone’s film is ultimately little better than a stunt, and a fairly toothless one at that.

Most everything in the picture is “factual” in a sense, though it’s clearly been edited down and simplified and a dollop of exaggeration has been added. That doesn’t mean that it isn’t, to a degree at least, sympathetic; nor does it mean that it isn’t to some extent an exercise in ridicule. In effect it straddles the two poles, inviting you both to perceive that here’s a guy totally out of his depth as president and at the same time to feel sorry for him as, in his clumsy, inarticulate way, he realizes that he’s in over his head. Periodically Stone uses a metaphor of Bush, attired in a Texas Rangers jacket, listening to the adulation of an unseen crowd in an empty stadium while desperately trying to catch long flies that threaten to go over the wall—an image that one can read in a whole variety of ways depending on your perspective; and that’s apparently the way he wants the whole picture to work.

Stone also offers what he apparently sees as the key to G.W.’s character in his strained relationship with his father, a man portrayed here as congenitally unable to muster up any praise for his son while repeatedly expressing disappointment in the poor fellow’s youthful indiscretions and, later, discomfort at the brazenly evangelical brand of Christianity Dubya ultimately turns to (and which the picture portrays without disrespect). The suggestion is that it was the son’s drive to succeed where his father had failed and finally earn his love and respect that led him to overreach as he did.

This is just pop psychology of the simplest sort, and it really doesn’t add much dramatic meat to the bones that Stanley Weiser has cobbled together from the historical record and inside gossip. What one’s left with, therefore, is the fun of watching the hand-picked cast do impersonations of famous people. At the head of the list is Josh Brolin, fresh from his great turn in “No Country for Old Men,” who may not actually look like Dubya but captures much of his manner and personality. (Speaking of keeping up with daddy, it must have been fun for Josh to match his father James’ portrayal of Ronald Reagan in the 2003 TV miniseries so controversial that it was ultimately bumped from CBS to cable.) Scott Glenn doesn’t make much of Donald Rumsfeld, but Richard Dreyfuss is a suitably manipulative Dick Cheney, especially good in his disagreements with Jeffrey Wright’s Colin Powell which, like Thandie Newton’s Condi Rice, is a bit too studied; and Toby Jones is an impishly oily Karl Rove. Often the effect, even with Brolin and Dreyfuss, is more like a “Saturday Night Live” sketch than anything else, but it can be a hoot. On the other hand, James Cromwell treats the senior George without any sense of mimicry, playing the part straight as a patrician with a stiff streak, and registers strongly, which is more than can be said for some of the less recognizable faces in smaller roles. (Ioan Gruffudd, for example, is a dud as Tony Blair. They should have gone with Michael Sheen, of “The Queen.”)

As with all of Stone’s films, “W.” has a somewhat garish but eye-catching look thanks to production designer Derek Hill, art directors John Richardson and Alex Hajdu and cinematographer Phedon Papamichael, who takes full advantage of the widescreen format. And certainly Julie Monroe has done a fine job of editing Stone’s rather erratic assemblage into a whole that moves well, even at over two hours, and maintains a fair degree of coherence despite the shifting chronology. Paul Cantelon’s score too often resorts to “The Yellow Rose of Texas” and similar stuff to make its point.

“W.” will work best for those who already know most of the incidents Stone and Weiser have collected and enjoy seeing them played out by such big names. If approached in the proper frame of mind, it can be empty fun (especially, one imagines, in an auditorium where alcohol is served). But deep it’s definitely not.