I saw Inception for the second time today. Major spoilers ahead.
I was going to write about why everything that happens in Inception is a dream, citing evidence such as the fact that the maze that Ariadne (e.g. the woman from Greek mythology who leads her lover through the minotaur's labyrinth by giving him a ball of string) first builds of the city layer is oddly similar to the city Dom and Mal built in Limbo. In fact, I kept a record of the quotes from the movie that support this, as my theory is that everyone's wish for Dom to be back in reality is based on one false assumption :
No one said you wake up when you die in limbo.
As far as we know, it might simply take you back up one level. There are 12 levels - and a basement - in Dom's consciousness. We don't know how deep he went with Mal. It could simply be that they killed themselves in Limbo, thus ending up in level 13 - the Basement - where Mal killed herself, either waking up or just bumping herself up to level 12, one level above Dom. She's still gone, and he's still trapped, but the important thing is this : everyone he meets actually comes from Mal's subconscious.
They could be projections of his own subconscious, but given how shocked Ariadne is when she finds out Dom used inception on his own wife, I don't think it could be his own projection. A lot of the time the other characters ask Dom questions, such as "What's down there for you?" and say things like, "Don't lose yourself." or "Come back to reality."
Anyway, a summary of my thoughts, for the most part, can be read at these two sites, which were the first two that came up in a Google search for my topic. Something I do find personally alluring about the world of Inception, though, is an idea (ha!). It's much nicer than in the Matrix, and when the question is, "If it's all a dream, does it really matter?", the Matrix says no while Inception says yes. The other thing I find comforting is the idea that, when we die, we might really have been asleep, and get to do it all again. For me, Inception is fantastically optimistic. I wish other movies left me feeling so overwrought, but content.