So, a while afterwards, let's make a point of this.
It's not worth the hype. The bit at the end seems like a bad cross between the Matrix and the Village. Not to say that the Matrix (at least the first one) was a bad movie. And, really, the only problem with the Village was its predictability. Twist endings have their place. They've become culturally ingrained enough that it's very hard not to telegraph them.
So, before we get into any great detail:
WARNING SPOILERS FOR AN OVER-HYPED MOVIE BELOW.
If you do not wish to ruin the plot twist of Inception, cease reading now.
You have been warned.
So. It's not really real. And there's multiple interpretations. Saito shoots Cobb, Cobb goes even deeper. Maybe Saito wouldn't come back. Maybe Cobb is dreaming on his own, really deep, like he did with Mol.
The problem is when people say "it blew my mind" you have to realize, this means that you have something of a poor imagination. Or else some people have rather large ones.
It's not really a mind-blowing revelation. Mind-blowing was learning when you were a kid, just how big something was. Or maybe it was learning that things could die? It altered your perception in such a way that your mind was expanded. That's the important part. Expanded.
So the idea that this whole world might not be real is shocking to you? You had honestly never considered that before? Are you actually reading this? Does it even matter? Look the point is, it's not a huge deal. Inception is not a bad movie. I'll admit, it ran a little long for my taste, but it's not horrible. It might even make an interesting mechanic to try to express in D&D.
It's just not as good as people make it out to be, and I think everyone needs to take a minute and think about it. It's a movie. It's different. I feel a little bad if you had never considered what the movie presents before.
But ask yourself:
Does this movie really mean that much?