First, the basic plot, for those of you lucky enough to have neither read nor seen this horrible novel and too lazy to read through the Wikipedia synopsis. Howard Roark is an uncompromising, individualist architect whose modernist designs are, besides being incredibly ugly, hated by the architectural establishment. Peter Keating is his parasitic conformist kind-of-friend and fellow architect, who is initially successful because of his mediocre talent and willingness to conform to the stylistic dictates of the establishment. Ellsworth Toohey is Roark's great nemesis -- the architectural columnist for The Banner, Toohey's desire is to control others by promoting a philosophy of conformity, mediocrity, and anti-individualism. Since Toohey cannot bend Roark to his will, he naturally wants to destroy Roark. Dominique Francon is Roark's love interest; more on her later. Gail Wynand is a newspaper magnate, editor-in-chief of The Banner. At the beginning of the narrative, Wynand has become wealthy and powerful by pandering to public opinion -- The Banner celebrates mediocrity and conformity, with Toohey as its public face. However, after encountering Roark, Wynand realises that uncompromising individualism is the only true virtue. While he endeavours to follow Roark's model, he is ultimately unsuccessful, and temporarily reverts to pandering to public opinion for the sake of his financial interests in the third act. For about half of the narrative, Wynand is married to Francon, despite her complete lack of affection for him.
In the first act, young Roark is spectacularly unsuccessful because of his unwillingness to compromise his unpopular designs, while Keating has rapidly risen to the top of the profession by embracing a mediocre and ugly design aesthetic. Roark is so unwilling to compromise his principles that he eventually takes a job in a quarry rather than produce ugly buildings. Meanwhile, Francon has withdrawn from a world of hideous mediocrity. Meeting Roark by chance, they are initially drawn to each other, but Francon is frightened of what a cruel, conformist world will do to an individual spirit, and withdraws. At the end of the first act, Roark receives a commission from an admirer of his work, a wealthy industrialist and `self-made man' who is otherwise unimportant to the plot.
The second act sees Roark's star rising. Toohey attempts to oppose Roark's success, inciting a public opposition campaign using his newspaper column -- a campaign which Wynand approves to increase the sales of his papers. This campaign is unsuccessful, and Roark receives commission after commission. Francon and Roark meet again, but again she is more worried about what society will do to an individualist spirit, and she runs off to Wynand. Several years later, with Roark a successful but controversial architect, Wynand commissions Roark to design his country home -- a `temple' to his wife. Wynand has complete forgotten the smear campaign against Roark, but Roark does not hold this against him. Wynand comes to admire Roark, and despite the romantic tension between Roark and Dominique, the three become close friends, a tightly-knit group of individualists. Peter Keating, meanwhile, has gradually lost his prominent position, and in a desperate bid to recover, agrees to attempt the design for a low-cost housing development. Due to his mediocrity, Keating is unsuccessful, and turns to Roark for assistance. Roark agrees, because solving the low-cost housing problem is something that happens to personally interest him (and not, in particular, out of any desire to help the destitute and homeless), but only if Keating does not allow the design to be compromised -- it must be built according to Roark's design, or not at all. Of course, this does not happen, and the establishment architects appropriate Roark's design `for the common good', modifying it. At the end of the second act, Roark destroys the nearly-completed development in an act of civil disobedience.
The third act focusses on Roark's trial. It is never clear exactly what the charges are supposed to be -- presumably, the destruction of the buildings owned by the developers -- but the two sides are Randian individualism versus the `collectivism' of the establishment. Toohey condemns Roark in the court of public opinion, Wynand betrays Roark by letting Toohey do it, but Roark triumphs in the end.
On to my analysis. In terms of a piece of literature and film, this thing is godsawful. The writing is stilted, hyperbolic, and repetitive, with all the subtlety of a brick in the face. Every single line is clearly intended to identify a character as either a noble individualist, a parasitic and contemptible conformist, or, in Wynand's case, torn between the two. To call the characters two-dimensional would be too generous. Every major character is either an annoying sycophant or an arrogant douchebag; none of them are in the least bit likable, but I suppose this is deliberate on Rand's part. Apparently we're supposed to admire the fact that Roark doesn't give a shit about anyone but himself. From a film standpoint, the acting is horrible, the music is overwraught, and the cinematography is listless and uninteresting. The passion between Roark and Francon is as smouldering and compelling as a bucket of water.
In philosophical terms, Rand is sort of the crib notes version of Nietzsche, only on steroids. Wikipedia gives a reasonable summary of Rand's individualism:
Rather than using "selfish" in describing choosing one's interests over and against the welfare of others, she described an act as "selfish" if it remained true to one's ideals against the influence of history and society. "Selflessness" is the concept of losing one's self, not merely acting without regard for one's self or in the interest of others, but as being unable to determine and form one's desires and opinions.
At least, this is what Rand says. She's not consistent in applying this, however. I'll illustrate this by examining each of the five major characters in turn. So, at best, this characterisation is an oversimplification.
Keating is the easiest: he is clearly shown to be unable to determine and form his own opinions and desires. However, he's not a villain; he's just contemptible and pathetic.
Roark is also supposed to be easy to categorise: he doesn't give a shit about other people's opinions at any point in the film, and therefore is a selfish hero.
But contrast Roark with Toohey, the great villain of the narrative. Toohey achieves greatness and power -- at least temporarily -- by manipulating the opinions and desires of others. But he clearly has his own opinions and desires. He's entirely selfish, in both the standard and Rand's sense: he chooses his own interests over and against the welfare of others (even as he appropriates this rhetoric for his own gain) and never compromises his principled, Machiavellian pursuit of power.
Furthermore, Roark's groupies -- Francon and Wynand -- should properly be seen as just as contemptible as Keating. They're identified as praiseworthy not for being individualists but because, unlike Toohey, they think Roark is the shiznit. The times when Wynand is portrayed negatively are especially telling: Wynand twice chooses to demonise Roark for the sake of maintaining his wealth and power as a newspaper mogul. Clearly, in these cases, he's acting according to his own desires and opinions -- like Toohey, he's choosing to pursue his own power according to his own best sense of the way to do that. So, like Toohey, he can't be fairly demonising for not being an individualist, because he acts in a selfish way (in both senses) consistently throughout the film. Rather, he's demonised when he doesn't kiss Roark's ass and sing his praises.
Francon's in a similar position. Up through the middle of the second act, Francon is portrayed as disgusted and fearful of the world. Roark's presence in her life, starting in the second act, finally gives her courage and purpose. She is clearly inspired by Roark's professions of individualism. That is, like Keating, she derives her desires and opinions from others -- Roark rather than Toohey -- and, hence, is no more of a true individualist than Keating. At the end of the second act, she happily risks her life to help Roark destroy the housing development, with no expectation of anything in return from him. Does that sound consistent with Rand's opposition to altruism to you?
Now, from comments Rand made throughout her life, it's clear that she identifies heavily with Roark and the other positively-portrayed selfish assholes of her works of fiction. Consequently, the real villains in Rand's universe aren't `conformists' or `collectivists'. They're other individualists who are Rand's rivals. Similarly, the real heroes aren't `individualists'. They're people with whom Rand identifies, and their groupies.
Rand's philosophy isn't individualist at all. It's a cult of personality, built around the worship of Ayn Rand, sycophantically praising her for her complete and utter assholitry.