SPOILERS AHEAD (I can only talk about the themes of the show and movie with the aid of spoilers, I'll minimize plot spoilers as best as possible)
This is an interesting movie as the overall primary relationships between the characters from the show and those in the movie are largely the same. Of course, anyone outside of Hitomi and Van get considerably less to do, but such are the time constraints of a 90 minute movie compared to a twelve hour show. However thematically the story of the movie is used to talk about something very different than did the show.
The TV show seemed to show us that man's attempt to change and control fate and destiny, even when its done for pure reasons, has unintended destructive side effects. It isn't so much a free will versus determinism argument as much as it is a warning against trying to get too tangled in controlling fate, lest you get bit.
The movie however, doesn't go there at all and instead is a story about suicide and loneliness. There's a sort of fictional logic to the idea that a young girl on earth's desire to kill herself would hold the fate of an entire fantasy world in thrall. Here Hitomi is a very sad and lonely girl who lives life and yet is untouched by it. Her yearning for extinction is what draws her to Gaea, and through the process of meeting Von and realizing that she doesn't want him to want to die, she sees the value of life. The message here is very much about the power of choosing to live even through times of pain and how even though we are alone, within love we are also united.
I think both themes and stories are valid and I love how the same director returned to the well and brought up very different results. I'm curious to see if the manga offers a similarly diverse look at the same root material.
