Have seen Inception twice and have purchased the soundtrack. I thought the film was beautiful and very intelligently written and executed. A mainstream film that makes us think - what a concept!
Both times I watched the film in an IMAX theater. The first was at the back of the theater - which was perfect. The second time was from the 4th or 5th row up and I found that the soundtrack drowned out dialogue on a few occasions and I had to cover my ears on most of the action sequences because it was much too loud.
I highly recommend the film, but ensure that - if seeing in IMAX - you're in very back of the theater.