A very good action flick and a good little twist at the end. There are a few holes you can start poking in the plot if you think about it too much, but mostly this serves to keep you guessing during the movie and only become apparent afterwards as you start to deconstruct the movie.
They could've easily added another 20 minutes and done a little more character development - but it would've slowed down the tempo of the movie, so I understand the reasons for their choices.
Angelina Jolie is fantastic, but the scene on the window ledge really shows just how thin she is (watch her legs/ankles/feet) - it's the first time I'd noticed it in any of her films and it made me a little sad.