Thirty-odd minutes into Knight and Day, the action-comedy concoction from director James Mangold (3:10 To Yuma, Identity), and things are looking surprisingly good. Tom Cruise oozes charisma, Cameron Diaz has pizazz. The story has me guessing, the action has me smiling. “This is great!” I say to myself, almost prepared to call this one of the more entertaining Hollywood blockbusters of the year so far.