Yesterday, finally, I got round to watching it & I can say with certainty that I wasn't disappointed.
Whilst, like most blockbusters, it has its flaws, it's probably one of the most intelligent of its kind for a long time.
I'm also always slightly biased when it comes to British directors, love Leonardo DiCaprio & <3 Joseph Gordon-Levitt since I first watched him when I was younger in Third Rock from the Sun and 10 Things I Hate About You (also igniting at the same time my love for Heath Ledger, R.I.P.).
The haters will be quick to jump on it, and it's by no means perfect, but in contrast to other big blockbuster films to which I shall name no names (Avatar), it's positively brilliant.
I desperately, desperately hope that a sequel will not follow, otherwise it will undo all the wonderfulness that was created, and will most likely destroy its reputation, much like The Matrix sequels have done to it.
I would strongly recommend watching it though, with others, loud & surround, on some ridic. size screen.
FOOTNOTE: I also LOVE Cillian Murphy. He's a beautiful actor to watch.