TL;DR: This movie was good but forgettable. Reading the book beforehand is a positive here and you will want to go see it, but keep expectations down and expect a radically altered story with no lasting impression. If you haven't read the book, prepare to be confused, but it can still be an entertaining ride.
Edition watched: 2D IMAX
The largest positive for this movie is Tom Hanks. Hank's role here is a slight departure from how he previously played the role, due to the circumstances that are made apparent from the very beginning (but I won't spoil), and yet he was excellent again as Robert Langdon. Aside from Hanks, the story was muddled but chase-movie action and constant changes of beautiful scenery makes this entertaining if forgettable.
I have read the book (and liked it) and I went to see it with 2 people who had not read it.
For those who haven't read the book, you should know that this is not like the other 2 Dan Brown movies. Those stories dealt with secrets and puzzles from many years ago (hundreds or thousands in some cases) and they had that Indiana Jones for the art history major feel to them. In this movie, all the puzzles are manufactured by a modern day character in the story, so it almost completely lacks that Indiana Jones feel. Even though I had warned my movie companions about this, both were quite disappointed by this aspect.
However, the biggest problem my non-book reading movie companions had was confusion. As someone who knew what was going on, even I felt the way they injected some story elements and then dropped them just as fast was a bit dizzying. Given that this movie was adapted for the screen and had radically altered elements from the book, the handling of the story telling was sub par.
Both of my movie companions felt the movie was entertaining but nothing special. One sentence opinion: "It was OK and I enjoyed it." and "It was OK, let's go eat."
For those who have read the book, in my opinion this movie departs radically from the source material. That said, reading the book is an advantage and might be a compelling reason to go see this. Knowing the book-story means you will know what is going on, even through elements that were not in the book and/or were presented poorly (e.g. skin rash). I found the changes made for a better experience since I wasn't just seeing a rehash of what I had read. That said, among several disappointments, I was looking forward to a Vasari Corridor scene and I was very much let down.
One thing to note, Dan Brown's message was pretty much lost and I wonder if that was intentional? Even the ending, which in the book was used to punctuate Dan Brown's obvious point, is radically changed in the movie. So while the basic story is similar, the actual take away I left the theater with was very different from the book. I mark this as negative because the book made me think about what I had taken for a given, the movie simply entertained me and went away afterwards.
Overall, as someone who read the book, I enjoyed the movie but did feel let down.