The title alone, plus its tendency to use shadows and have people framed in narrow corridors, shows that the theme isn't transsexualism, but the feeling of being trapped.
It's neither anti-gay nor pro-gay. In fact, Bidin's gayness is taken as a given. But his passivity (which is nowhere shown to be linked to his sexuality) ensures that he always makes the wrong decisions at the behest of others: first his boyfriend, then his (dead) father, then his mother, then his "girlfriend." As in the works of Rainer Werner Fassbinder, the protagonist here seems to be masochistically complicit in his own victimhood. This will dismay those who think that protagonists should always be role-models of some sort (call it The Oprah Syndrome), but it's also an affective way to open up the power relations in the society it depicts.
The film this most closely resembles is indeed Fassbinder's In a Year with 13 Moons. It's similarly daring in its use of silences, and also potent visual metaphors (the abattoir opening of the German film is replaced with a dead tree-stump here).
A well-choreographed and strikingly scored wedding scene near the end is a gender-reversed homage to the opening of U-Wei's Perempuan, Isteri dan Jalang, which was in turn a modern homage to the climax of Salleh Ghani's Sri Mersing. And a nearly wordless scene in a bedroom right after that is one of the finest achievements in Malay cinema.
Although hamstrung by a low budget (the dialogue dubs sometimes sound like they were done in somebody's bathroom), the pithy and elliptical conversations achieve a remarkable degree of verisimilitude. It's a rare local movie (aside from the works of Ho Yuhang and Tan Chui Mui) that makes it seem like we are actually eavesdropping on real people.
Its refusal to present Bidin's gayness or his transsexual condition (he's not a genuine transsexual) in slapstick or monochromatic terms already puts it way ahead of the much shoddier and sleazier 2 Alam. But its relentless dourness can make it a discomforting experience. The (mostly nocturnal or interior) cityscape is a place of liberation but also of constraints, as can be seen in Bidin's financial situation and also his boyfriend's smoking addiction.
A bare-bones synopsis, plus some rash statements by its producer Raja Azmi, can make you think this is a reactionary and judgmental freak-show. But the screenwriter/director Khir Rahman seems to have done a lot to make ... Dalam Botol a much more complex experience. It lingers. This a film that doesn't let anyone (including its audience) off the hook. My take on this film is exactly what Yasmin Ahmad had said about Raja Azmi's previous film Haru Biru: "I don't care what weirdo produced it, I quite like it!"