Very good.
I'm especially happy that this was more of a Mission Impossible than just a generic action movie.
Truth to be told, Mi 2 wasn't horrible. It was a decent stylized action flick. Except it was 'The Amazing Adventures of Ethan Hunt' instead of a Mission Impossible.
The extended Vatican sequence was a true Mission Impossible moment. Team works, gadget, wits... The first sequence in Mexico was also Mission Impossible lite, but still in the vein of the serie. The ending is more traditional and focus on Hunt but at least we have had our MI moments and these action sequence after the Vatican are fairly well done. The bridge in particular.
So all in all, a good action movie. We're not talking oscars here, but this could be the best traditional action movie of the year
PS : Traditional action movie means it focuses on stunts, gun fight and explosions. Not wire kung fu or CGI (which has it place, mind you!).