Nicely done.  I love sci fi but there is so much more bad sci fi than good sci fi.  This definitely falls in the "good sci fi" camp.  My only quibble is that Ethan Hawke and Jude Law don't look enough alike for Hawke's character to plausibly pass for Law's.  But that's a minor detail.  Perhaps less minor but still not overwhelming is the lack of development of Hawke's character that would explain why so many people are willing to help him, including Thurman's character and the lab guy, whoever he is.  But it's still a better sci fi movie than most.