Best MI yet? You don't need to know anything from the previous movies coming into it. It held my attention the entire time and suspended my belief well. It was better than skyscraper. The actual stunts are awesome. I recommend seeing it on the biggest screen you can.
My biggest complaint is with mustaches. After being hyped so so so much, the mustaches in this movie don't play any significant role that a bare upper lip couldn't have. The mustaches also aren't that massive, they seem fairly young.
We saw this in an ATMOS theater and the soundscape of ATMOS continues to amaze me.