I saw it in IMAX, too. I forgot, initially, that it was HFR, and at the very beginning when Bilbo opens a chest and looks in, it looked like his facial expressions were moving WAY too fast. Not, smoother, not cleaner, just faster. The film looked sped up, and that effect lasted the entire rest of the movie, some scenes more pronounced than others. I like the 3D, but it’s not really critical to the film. I’m seriously considering just straight 2D for the next one unless some major improvements are made.
I expect to own all the movies, and they will be in 2-D (I don’t expect to ever do 3-D TV), so I figured to watch the 3-D in the theater.