bethnor - I think you're completely wrong about it not mattering whether or not the end is a dream - I think that point is what the entire perception the audience has of the movie necessarily hinges on: what is reality and what isn't? How much of what happened came from Cobb and how much, if any, was reality? again, my problem with the film is that reality and dreams were so alike that the distinction was irrelevant to me. i very nonchalantly agreed with mal when she pointed out to cobb that his "real" world was full of anonymous corporations, etc., etc. it wasn't a stretch at all to believe that reality was a dream or vice versa as they were basically the same. i think it's very telling that some viewers think of "mission impossible" after seeing this movie; you could lift any scene and comfortably place it in any other "caper" movie and it would fit just fine.
other films have done a far better job of blurring the lines between what's real and what's not, like pan's labyrinth. you have no choice but to accept that ophelia used the chalk to escape from the room, but at the same time something like that can't happen in the "real" world.
here's the trailer for "limbo" for the xbox, which contains the elements i felt were lacking in "inception": a world which doesn't contain a ton of fantastical elements so it can seem real, but at the same time there are undercurrents of something terribly, terribly wrong, that the character is trapped in something he can't escape from, a world that is both real and abstract:
http://www.youtube.com/watch?v=bV-0w8I-oAc