They were showing it every 30 minutes so it was not packed at all - we went to see the 2D version.
I could see in the first 5 minutes what they meant about the difference in 24 fps to 48 fps. After that, I mainly noticed it in close-ups and scenery. Close-ups did not have pores like you would normally see - and the scenery was brightly colored.
However, I was so immersed in the film I did not even notice it much after that first 5 minutes. As I expected, Jackson dod a really good job transferring this to screenplay - the story flowed very well with the book with just a bit of theatrical addition. And, as in the first 3, specific points of dialogue were pulled verbatim from the book.
I did hear someone complain about it being too much of an action movie on the way out. Not my take - but there it is.
All in all - a great start to this series. And, I called the exact spot where this one would end! :flex: