I added Tarnation to my film queue on Lovefilm quite some time ago, and if I remember rightly, I was interested in it for the very shallow reason that it was entirely made using iMovie. However, it turned out to be a somewhat unique film for other reasons, and well worth watching. I should point out that it's not the kind of film to watch if you're in the mood for a light, entertaining film. It's probably one of the most harrowing, disturbing films I've seen recently.
Jonathan seemed (and still seems) to use the camera as a diary or confessional. He is painfully honest to the camera, talking about his feelings about his mother, and his feelings about his homosexuality, except when he acts out monologues, for example by playing the part of an abused woman who has murdered her husband. You get the feeling that he was hiding his own pain behind that of some imagined character.
The film comes up to the present day following his mother's attempted suicide and the deterioration of her mental health, and his continuing relationship with her. Her prognosis and their history is so bleak, and yet through it all, he still loves her and feels connected to her. There's a heartbreaking moment when he's talking to the camera and taking a break from the exhausting business of interacting with her, and he breaks down with real fear in his eyes saying that he doesn't want to end up like his Mom. He does at least have some hope in the shape of his lovely, stable boyfriend David, who seems to be about the only safe harbour in his life.
It really is a unique and remarkable film, but one that's difficult to watch.