Not everything old is wonderful. Smallpox, high infant mortality, and non-air-conditioned homes are but a few examples.
I just finished watching this, or, rather, most of it. I think it's another good example that one cannot count on something being good simply because it's old or has remained popular for a while. The film simply was not very good.
That is not to say it had no redeeming qualities. The stop-motion animation was some of the smoothest I've seen, and there is some extremely clever editing used to incorporate it into the rest of the film seamlessly. However, the propsmaster of the film should have been fired, as everything looks cheap and toylike. Even the stop-motion models are flaw-ridden and poorly crafted.
That's without even looking at the plot. While I understand that the film is essentially tropic: it tells a story we've already heard many times, it uses this as an excuse to basically deus ex machina away any potential tension or thrills. Perhaps they could get away with this in 1963, when the film simply being in color was novel enough to wow audiences for over 100 minutes, but today it's a bore.
Even the score is mediocre, ranging from simply boring to annoying and bizarre.
I may pick it up again and finish it properly later. Who knows? Maybe I'm just grouchy tonight.
Of course, there are old films which; I would classify as very good, and in many cases world-class. Jason and the Argonauts simply isn't one of them. I chalk its continuing popularity down to the Baby-Boomer Phenomenon.