“Shortbus” is like a pornographic film except the graphic sex is not supposed to turn you on and the movie has more ambitious storylines. If this first sentence makes you uncomfortable, this movie is not for you.

In fact, a good number of pornography genres are accounted for and nothing is stimulated. The first ten minutes are explicit sex scenes. Two minutes later, the next 10 minutes are explicit sex scenes. This does not even include the orgy scenes the film uses as mere background for conversations.

The movie centers around what director and writer John Cameron Mitchell (the mastermind behind “Hedwig and the Angry Inch”) calls a “modern-day multi-sexual underground salon” called Shortbus. The salon gets its name because the people who frequent it identify more with those who ride on short buses than the normal folks who ride on normal long buses.

The film is the result of three years of workshops and dialogue between the cast and Mitchell. “Shortbus” has that spontaneous feel of improvisation and ad-libbed one-liners like a Vince Vaughn or Christopher Guest movie.

It’s one of those it’s-a-small-world movies set in New York, complete with a scene where the camera is situated on one character and then moves on to another character who has just entered the screen without either character knowing who the other one is.

However, Mitchell may have broken new ground when the first character is a picture-taking, possessive stalker of his neighbors and the second character is a female dominatrix.

Of course, what Mitchell has really challenged cinematically is America’s attitude toward sex and its influence on movies. Sure, people engage in all sorts of sexual acts on-screen, but don’t you see, these characters also have issues and problems. Sex is just a metaphor!

Take James (Paul Dawson), formerly known as Jamie. He’s creating a video for his boyfriend Jamie (PJ Deboy). In the opening scenes, he tapes himself when he’s naked in the bathtub and when he’s attempting the man’s man of mythical masturbation moves.

Ah, but underneath that beautiful, chiseled face with the perfect lightly shaven goatee and mustache is a tortured, brooding soul. Luckily for James, all his troubles go away with one angst-filled sexual act.

The heroine of “Shortbus” is Sophia (Sook-Yin Lee) who one would assume loves having sex with her husband Rob (Raphael Barker), if the first 10 minutes of the movie are any indication. They are a rather acrobatic pair. But she has never had an orgasm. The sex therapist/couples counselor spends most of the movie trying to achieve one.

One of the best sequences in “Shortbus” looks like a choreographed musical sequence of a threesome. In their newly declared open relationship, the Jamies bring home Ceth (pronounced “Seth” played by Jay Brannan). There is synchronized turning and a rendition of “The Star Spangled Banner” that you have to see to believe.

Another notable scene includes the couple’s exercise used by Sophia and Rob. On the verge of a fight, the first step is to sit cross-legged across from each other and scream. The growing relationship between Sophia and the dominatrix, Severin (Lindsay Beamish), rivals that of any womanhood movie. Justin Bond, that fabulous transvestite and drag queen from New York, plays the Madame of Shortbus and he steals every scene he’s in.

The first half of the film is hilarious, innovative, deep and witty. The second half becomes too serious for its own good, a little too self-congratulatory. The characters are stretched by the plotline in ways their sexual partners have never tried. The ending is questionable. Everything is just a little too happy. A marching band crashes the Shortbus, for goodness’ sake, and everyone smiles and smiles.

The movie seems to lose a little something in the ending. Maybe there’s just not enough sex going on.

There will be people who will worship “Shortbus” and its message and will hold the movie up as a sophisticated artistic expression of young people. There will also be those who will be disgusted by the blatant sexuality and denounce the new low films have reached.

And then there will be the middle group who enjoyed the ride, but found the movie lacking in stamina to go all the way.