This is an absolute classic.
The premise is fairly interesting - some girl, Tita, is the captain of a spaceship which collects rare animals. Nice idea, which turns out not to be the focus of the OAV at all. Tita saves a girl who just happens to be being hunted by some evil guys. The chase begins!
But that doesn't matter, because the real charm and brilliance of this anime doesn't lie in the dodgy story, bad music or waifs of character personalities. It's in the most beautiful and stunningly designed breasts in anime. That's right; the reason I've watched this dozens of times in the last dozen or so years is the awesome tits. Satoshi Urushihara is the king of drawing truly beautiful female characters. Not just the boobs, the whole character is stunning, and invariably beautifully coloured.
His manga and limited anime is peppered with such beautiful women. If you thought there was no such thing as hentai without rape and general mysogeny then check out his Another Lady Innocent anime or Nostalgic Heroines artbook.
But this is far from hentai, it's just eye-candy, and I love it. Even Jonathon Ross has admitted his love from this one!