I have to make one thing clear: Space Fantasia 2001 Nights is NOT an anime for everyone. If you want to know if you will enjoy this, just answer these question: Do you like Golden Age Sci Fi, like the novels and short stories of Arthur C. Clarke or Asimov? Do you think that Star Trek TOS is the best Trek? Can you tolerate 80s anime art and animation? If you, just like me, say yes to all of those question above, you will definitely enjoy this hidden gem. This short OVA is a great homage to the now extinct species of old hard scifi, focusing on realism and the sense of wonder at the expense of characterization and conventional plot. For those unsure, here is more detail about various aspect of the show:

Story: like I say, typical Golden Age sci fi done right. Very realistic in the science(as much as they can afford to), with interesting twist and epic scale.

Characters: The OVA is short and not about individual characters. Not for fan of character-driven fiction.

Animation and art: 80s anime art style. The aesthetic is nice, but the animation is not. Lots of panning to hide the lack of movement. Pleasant to look at, but don't expect too much.

Sound and music: strange 80s music. May not for everyone, but fit the OVA perfectly.

Overall I gave this anime an 8 out of 10.