I'll probably get flamed for this one, but... After many years of hype, I really expected to get completely blown away by Indiana Jones. Granted, it is a fabulous attraction - truely great. But, I didn't have that "holy cow" moment that I expected. Perhaps because my expectations were set so incredibly high over the years. Again, don't get me wrong, it is a great attraction.
I heard so much about how great the queue was, but I've experienced an equal (perhaps even better) queue in Dueling Dragons. Also, I think the ride system amazes many first time riders, but having experienced the ride system many times on CtX, that didn't add to the experience. The effects were great, but you get bits and pieces of that in attractions such as Revenge of the Mummy (which does pale in comparison, overall, to Indy - of course).
I guess I expected it to be the best theme park attraction in the world (by a long shot). But it wasn't. I recall my initial reaction to Spider-man being stronger.
So, concluding, I think had I experienced Indy without ever having been on Dueling Dragons (to see such a queue), Spider-man, Revenge of the Mummy nor Countdown to Extinction - I would have been totally blown away by the attraction.
There are plenty of attractions that, while perhaps not underrated, really wow-ed me unexpectedly. First is the Storybook Land Canal Boats. What an amazing level of detail in the miniatures and the landscaping. It is a nice, long ride and very well narrated. And, we happened to ride on the "goldenized" boat, which added to the experience.
Second is the Casey Jr. Circus Train. Similar scenes, but from a different perspective. The train ride is nice and long and the soundtrack (including the "i think i can" portion) adds a lot. I was very glad we experienced it.
Third is Alice in Wonderland. A full three minutes in length, it is about 50% longer than peer attractions such as those of Mr. Toad, Snow White and Peter Pan. The Playing Cards scene was a real surpise, and the outdoor slide down the leaf was something we'd never get down here in Florida because of the weather.
Fourth is the Enchanted Tiki Room. It had been so long since I had seen the first version that played at WDW, it was a real treat to see Walt's original.