What makes Ryan Murphy such a frustrating storyteller is that he has very obvious and impressive strengths, which he then seems to go out of his way to obscure with his very obvious weaknesses. He has great passion for socially relevant drama, for instance, but his point tends to get lost in the ADHD style that eventually plagued "Glee," "Nip/Tuck" and everything else he's done in television. ("American Horror Story," his biggest current hit, at least started out with ADHD, so there was no letdown later when things unraveled.) He works well with actors as both a writer and director, giving them meaty material and pulling excellent performances out of them, but then makes various other choices that distract from those performances.

That "The Normal Heart" — an adaptation of Larry Kramer's 1985 play about the early days of the AIDS crisis — has finally been turned into a film that will air on HBO on Sunday at 9, after decades of sitting in development hell, is a testament to Murphy, who bought the rights with his own money and assembled a cast fronted by Mark Ruffalo and Julia Roberts. The film wouldn't exist without his belief in it. And yet I wish almost anyone else had directed it.

The story is a roman à clef about Kramer's days as one of the founders of the advocacy group Gay Men's Health Crisis — here, he is writer Ned, played by Ruffalo — and such an abrasive, unflinching spokesman for the cause that his friends first see him as an embarrassment, and later an obstacle to getting funding to find a cure for this mysterious "gay cancer." Roberts plays Emma, one of the few doctors in the city actively looking into the disease — as a wheelchair-bound polio survivor, she can relate to the idea of a mysterious disease that turns you into something the rest of society would rather not think about or interact with — while Ned's colleagues at GMHC are played by Taylor Kitsch, Jim Parsons (reprising a role he played in the play's 2011 Broadway revival) and Joe Mantello (who played Ned in that stage version). Matthew Bomer from "White Collar" plays Felix, a closeted pop culture writer for the New York Times, who won't risk his job to push for more coverage of the epidemic, but who will become Ned's lover.

The material is as much about the politics of the gay community as it is about the devastation that AIDS brought upon it. Ned's greatest contempt is saved for men whom he believes actively impede their efforts to safely stay in the closet. (He gets in trouble for trying to out Mayor Ed Koch during a live TV appearance.) And when Emma suggests that Ned's friends tone down their sex lives for a while until medicine gets a better handle on the disease, he tells her, "Do you realize that you're talking about millions of men who have singled out promiscuity as their principle political agenda?"

As Ned and his friends wonder why doctors and/or the government aren't doing more to fight this plague, "The Normal Heart" turns into a fascinating companion piece to 1993's "And the Band Played On," one of the best, most watchable HBO movies of them all (both films even feature B.D. Wong in small roles), which shows doctors at the CDC dealing with those same questions on a national, even global scale.

"And the Band Played On" was directed by Roger Spottiswoode, a journeyman shooter who seemed to recognize that the best approach to this rich, sprawling material and his all-star cast was to trust in the inherent power of both and get out of the way as much as possible.

Murphy has never had much luck with getting out of the way of his material or his various flaws as a filmmaker, and the opening segments of "The Normal Heart" — particularly a long party sequence on Fire Island — are presented in a flashy, attention-getting way, yet they do a very poor job of actually introducing the characters and their relationships with one another. Early on, we see Ned sitting alone and looking sad on the outskirts of a party, but have been given no indication as to why he's feeling this way. Later, he helps a drunken friend clean up in the shower and jokes that he once fantasized about getting him naked like this, even though there's been zero indication of an attraction to this point in the movie. A flashback to Ned and Felix's first meeting is for some reason presented as a porn-y bathhouse commercial. And when one AIDS-stricken character collapses in the street, it's shot with so many different stylistic gimmicks at once (Murphy's big on Dutch angles here) that the attempt to make the play feel more cinematic just winds up undercutting whatever visceral impact the scene is supposed to have.

That said, working with actors is a part of directing, and Murphy does wonderful things on that end. This is the best work Bomer has ever done, even beyond the physical transformation he undertook (losing 40 pounds during a break in filming) to portray the ravages of AIDS on Felix's body, and the scenes Ruffalo plays with both him and Alfred Molina as Ned's homophobic brother are overflowing with complicated emotions. Parsons isn't exactly a chameleon, and there may be moments where you watch him as self-described "Southern bitch" Tommy and wonder how Sheldon Cooper came to be running an AIDS hotline, yet the same physical presence and vocal delivery come across as much warmer and more vulnerable.  Nearly every actor gets at least one meaty monologue — there will be a moment when you'll realize exactly why Roberts took the part, above and beyond whatever bond she and Murphy developed while filming "Eat, Pray, Love" — and all deliver. Parsons is wonderful delivering a bitter eulogy where Tommy notes that funerals have become the center of this community's social life. Yet Murphy doesn't always do a great job showcasing those very performances he's drawn out; that funeral scene, for instance, spends much too much time showing the grieving attendees and not enough actually showing Parsons.

At a certain point in the production, Murphy seems to have recognized just how much less can be more with material this potent. The film's second half is shot in a more unadorned fashion, and when Murphy simply lets an emotionally charged scene — an argument at the GMHC office, or Ned getting a look at the physical ravages of the disease on Felix, or an intimate declaration of love in a hospital room — play out with minimal flourishes, it's gangbusters.

Ultimately, the good in "Normal Heart" outweighs the bad, which isn't always the case with Murphy's work. It's an important story packed with vivid individual moments, but with this material and these actors, it feels like it could be so much more than what it is.

Alan Sepinwall may be reached at sepinwall@hitfix.com