He had to be dreaming at the end, and IMO this was given away an hour previous. When Cobb's wife commits suicide, she's across the street sitting on a different building and Leo's saying "come step back inside" like she's just supposed to fly over to him ... and he doesn't need to shout for her to hear him across the street, and any investigator would know she didn't jump from the trashed room across the street from her.
I think it was simply meant to be a representation of how he couldn't reach her, which is also why that room (from what we could see of it) was the same as the room Leo was in.
Having said that, at the end, the Caine Character is wearing the same clothes as in Paris which I took as a possible sign as Paris.
More generally, while I found this a well-made and complex film it simply didn't engage me on a emotional level and I left the cinema thinking "so what?".
That's an interesting idea, and an elegant metaphor, but it's said explicitly that what is in Cobb's elevator world are memories, not fantasy, metaphors or dreams. They're supposedly literal scenes from his past he'd like to change. If so, there can be no metaphor of Mal being across the street waiting to jump as symbolizing his inability to reach her, which to me doesn't really make much sense (nor does his wasting time chatting with her at the end of the film in limbo) since he visits her in dreamland daily, and it'd be inconsistent since the other memories all appear to be literal and there are no other obvious metaphors in the film.
Discussing in general ...
Making up an excuse that it's a wrap-around building but we're not shown it, as someone else did, doesn't even being to fly. That's far too unusual to presume. The film is deliberately a riddle to some degree. This scene glaringly sticks out so it's either an unlikely massive technical error in continuity (in the filmmaking sense) or it's meant to appear as ludicrous as it is with her magically being across the street. Either it all means something - which is that Cobb's dreaming the whole film (maybe being psychoanalyzed or implanted from an upper layer by Ariadne which we are not shown in the film) - or it's a very poorly executed scene that doesn't clearly convey whatever else the director/writer may have intended.
And where are the people in the street or in other suites - no witnesses? No signs of struggle on Mal's body despite the room being trashed and her being thrown to her death somehow from across the street? Was this a comedy?
I agree with your last sentence, and with the criticisms I've read in the negative reviews of the film. Thoughtful and fair critique don't alter my enjoyment of it, but it does reveal how much better it could have been. As someone elsewhere asked - why the boring Matrix-y men in suits shooting guns as subconscious defense, why not pink elephants shooting lasers from their eyes? Visually that'd have been a blast ! Logically, if the subject/target is dreaming and self-defending, what's wrong with knowing it (due to absurdity) and waking up?
And why were the subconscious of the non-main-dreamers so often populating the shared dream world, but only when it suited the plot. Unless it was all Cobb's dream, then why is Mal and a freight train showing up, and alternately why can't he make shields and jet packs show up while the Aussie character can apparently conjure a rocket launcher? Why is the subconscious army still attacking if they're not in Fisher's dream in each level, and even if they are then why is his subconscious shooting at himself and his supposed protectors when he knows he's dreaming?
If it isn't all Cobb's dream, the movie is a giant crock of conflicting shite structurally and logically (arguably it is in any case), but still damn entertaining.
The actors don't even know what's going on - [COLOR=#0068cf]http://nymag.com/daily/entertainment/2010/07/inceptions_dileep_rao_answers.html?utm_source=feed burner&utm_medium=feed&utm_campaign=Feed%3A+nymag% 2Fvulture+%28Vulture+-+nymag.com%27s+Entertainment+and+Culture+Blog%29[/COLOR]