The big thing is size. They're nice, large, hard cover books. They seem to be decent quality though I haven't had mine long enough to start falling apart. The pictures are big and clear. I think I have most of his books on .pdf but the reprints are worth it. I don't think a computer or e-reader do the books justice.
"Astronomy offers an aesthetic indulgence not duplicated in any other field. This is not an academic or hypothetical attraction and should require no apologies, for the beauty to be found in the skies has been universally appreciated for unrecorded centuries."