As I said, it's a good spy movie. We never find out what the widget is. The bad guy is USDA Grade A Sociopath, almost too sadistic, but only almost. The twists in the plot aren't 100% obvious. You really could go either way with Ethan making it out of the movie alive. None of the technology is ludicrously bad, and Tom Cruise does trigonometry by hand. It made me cry.
Expect spoilers in the comments.
PS - The black dudes are awesome. Sadly, there is no Mo Movie Moment.