See this movie ONLY if you're a Gerard Butler fan, a London fan, a US Presidential fan, an action movie fan, a Ghayal Once Again fan......etc.
In short - really way, way too much of a good thing. It starts off well enough, but drops an octave of credibility every few minutes, until you're eventually left with the impression that the City of London is little more than a haven for misguided terrorists and incompetent policemen - and that it always takes just one man to bail out the President from impossible situations.
On a lighter note, don't miss the title credits at the beginning as well as the end. The names are really incredible - the screenplay, for instance, is by a guy named Creighton Rothenberger. Jeepers, that's 21 characters, even more than Alejandro Inarattu, whose movies at least win Oscars.
I hope to God we don't have a Paris Has Fallen after this. Even if Gerard Butler is producing.
