One of the main things I liked about the anime wasn't so much its story (I think in many ways the manga was generally more poignant on that front), but how incredibly (Relatively) realistically they depicted space travel by anime standards. No noise in a vaccuum. Cancer out the yinyang from radiation. Invisible lasers, non-aerodynamic orbital craft, and of course the diapers. None of this skipping around in space catsuits with motorcycle helmets crap. (Gundam, Bebop -- I'm looking at YOU.)
For a guy like me who grew up with an astronomyfag dad, it was rather incredibly refreshing to see a space anime that didn't have thrust vectoring or smoke in space or any of that other crap. Just nice mundane SF technology to allow more of the human element to shine through.
Also, Edel was full of win and piercings.