Decades later, still the most iconic performance of Superman of all time, Christopher Reeve humanized the Man of Tomorrow in a way that still often eludes comic book writers (leading them to do wildly incomprehensible things, like stripping him of his powers entirely) and has made it difficult for filmmakers to bring the original Cape into a modern context (evidenced by Man Of Steel to make a more critically positive impact, even though I, as did most pre-M.O.S. fans of Superman, loved the interpretation).
But for me, there's not many others who can claim a link so strongly to a character, especially a comic book one, like Reeve did for Superman. Critics and fans alike will argue endlessly over the best live-action Batman (Keaton, West, or Bale, take your pick), while everyone is pretty unanimous on his animated counterpart (the great Kevin Conroy. Also, Joker is pretty much unanimously spoken for in Mark Hamill). Spider-Man may eventually favor Andrew Garfield overall, but it's hard to disconnect entirely from a well-acted Tobey Maguire. And we're already getting another one soon. The Incredible Hulk's had three excellent actors portray him on the big screen. We have two different generations of Professor Xavier and Magneto. Routh, Reeves, Cain, Welling, and Cavill... all pretty great in the role of the Last Son of Krypton, but Christopher Reeve was just something special.
I argue that the portrayal stands the test of time, especially if you stick to the first two films. He's the squeakiest-clean of all the heroes, but he's never grating, he's never too much. Some of his powers are a bit out there, but the thing is, you can hate that, but you can't fault Reeve; he grounds it unquestionably by bringing that same hope and passion that Superman is known for, the real qualities he should be celebrated for, instead of ridiculed for.
Last year at Comic-Con, they had the 1989 Batman costume and the 1978 Superman costume side-by-side at a display. I was heartbroken thinking about how that version of Batman/Superman would never be. Reeve was a talented actor, and got to be the first real person to bring a larger-than-life hero to the big screen, arguably the largest of them all. And the most difficult of them all.
How do you make people care about an alien who is nigh-on invincible?
You play him like Christopher Reeve.
Happy Birthday, sir. Thank you for everything.
P.S., for non-Superman film buffs, I'd recommend The Bostonians and Somewhere in Time, for some strong Reeve roles. Also, a personal favorite of mine, Noises Off. Reeve holds his own against comedic greats like John Ritter, Marilu Henner, Carol Burnett, and Michael Caine.