If your a fan of what I'd call "Classical Electronic" Vangelis certainly should be a staple in your collection.
Most people became aware of him through soundtracks like Blade Runner or Chariots of Fire,
I cued into him with works like "heaven and Hell" and Spiral... which even in the late 70's would be a late comer to his work!
So he certainly has more great works then just the two soundtracks.