Tron: Legacy was fun. I saw it in the theater in its original run and enjoyed it. But it's far from being a beloved classic or even a cult classic. When you hear it mentioned, if people know it, the most common thing you hear praised is its soundtrack (and rightly so). But that's about it. From a visual standpoint, they did a few impressive things, but there's nothing amazingly innovative or different about it's aesthetic. It's a good CGI flick and it looks like a good CGI flick.
The original Tron, however, was the groundbreaking one. It is absolutely a cult classic. It has a visual style that was never done before or since. No other movie in history has ever been made using those techniques, many of which were literally invented for the film. Even today, with all the modern CGI eye candy that we are used to, it is visually striking. Not to mention the performances in it from the actors are wonderful and the score is beautiful as well.
In short, I think Disney has made a mistake here by focusing entirely on Legacy and not at all on the original. I know that the Hollywood mindset is always that "new is better" and, also, Legacy was made during the Iger years. But I think a ride that was based on the style of the original, or at least had some elements of both films, would have been a better choice.