Yup, I've seen it too now. Saw it last night.
How was it? Really good. Ground-breaking effects, great cinematography and an awesome soundtrack.
Although it had some pretty weak dialogue for some of the characters and the story was very predictable.
But I have to give it props for being almost 3 hours long and keeping me entertained all the way through, something many 3 hour movies have failed to do.
I still think District 9 was the best movie of 2009 though.