The story is beautiful: about a boy and girl that get separated, by space and time. He stays on earth, she joins the UN Spacy in a 'Tracer' (a one-person mecha). Her training is on Mars, and she keeps in touch with her boyfriend via SMS.
Then the campaign against the Tharsians (aliens that attacked a Mars base and apparently the source of the deep space-faring technology of the humans) starts, and the ships move to Jupiter. The SMS'es take longer and longer to reach earth. The two get separated further and further, and at the end, it takes 8 years to reach earth.
The story is top-notch. We see space battles and all, but the real focus is on the feelings between these two young people, and how their separation ("through the years and far away", as the title song goes) does not diminish their feelings for eachother.
Visually, the piece is stunning. The renders are really good (check out the warping spaceships!), but the character animation is so-so. What makes it extra-special is the fact that it was all done by one man. Yes, that's right, one man made a really succesful 25 minute OVA, on his Mac. There's even a voice-track with him and his fiancée as the characters.
bakenius, I'm thinking you should check this one out, I think you'd like it -- for the story, but also for the animation and the directing.