People who make large-format movies - shot on special 70-millimeter film and meant to be projected on massive screens - still haven't risen to the challenge that many IMAX theatres create. Most venues are located in educational institutions and need to draw a large volume of patrons to justify their costs; as a result, films need to have some educational value, appeal to a wide audience, and run about 45 minutes to allow for hourly screenings. But the IMAX films I've seen pay lip service to both education and entertainment but don't provide either very well.
In Journey into Amazing Caves, there's no real story - cavers simply explore a cave here, and then explore a cave there - no narrative suspense, and no knowledge imparted. The total educational value of Journey can be summed up in a single sentence: Very small organisms can have a very large medical utility.
The reason to see an IMAX movie is for the immersion of the experience. The picture and sound are superior to anything at your local multiplex, and the results are often thrilling. The magnitude of the image means that IMAX patrons seem to feel camera movement. Cinematography in IMAX movies is generally stunning as well, and the Arizona desert and ice caves in Journey provide particularly breathtaking visuals.
But the thrill that accompanies the best moments in IMAX movies is fleeting, and the overall experience - for me, at least - isn't fully satisfying. Educational films can be fascinating and entertaining - see, for example, the wonderful Microcosmos, or for older audiences, A Brief History of Time - but it's clear that large-format filmmakers are still afraid to deviate from the formula.
The large-format movement has only become popular in the past decade, and it will be interesting to see how it evolves. IMAX movies are in their infancy, and like any young medium, novelty rules at this point. Eventually, audiences will become bored by the uncomfortable adventure/education hybrid formula and demand as much from IMAX as they do from their regular films and television programs.