Too long by about thirty minutes. Pare the action scenes down. The explanation of the concept was too convoluted. It is a fanciful concept, so why waste time trying to convice people it is somehow quasi scientific? It would be better to simply state the concept of sharing dreams as the basic paradigm of the movie then move on to the plot. And the "is it or isn't it" ending seems more a function of lack of imagination on the part of the director than creativity. A whorthwhile movie to see once. Skip the IMAX, but buy the DVD when it comes out.