Finally watched the Japanese version all the way through for the first time a couple of days ago and really loved it. Loved all the little scenes here and there that got cut out in the Americanization process. They really add a lot to the film!
The American version never really did it for me and because of it KKvsG was always towards the bottom of my Godzilla list in terms of how much I liked it. Particularly loathsome is how they totally nixed Ifukube's fantastic score for a bunch of stock cues. Blah!
My biggest beef with the film is the blue tint to the bluescreened shots. I mean, bluescreening wasn't at all perfect back then but look at the bluesceen shots in The Mysterians - they actually match in color to their surroundings! Dunno what happened with this film though. Always bugs me to see it.
Still love it in its original form, though. Yet another Toho classic!
Funny though, my dad actually saw the Japanese version of this all the way through before I did!