I thought it was too long and the non-book scene to please the fans of the trilogy was unnecessary.
I watched the 48fps version. Didn't get sick, but there was a scene at the beginning where I could only see different shades of gold and the first shots of The Shire were a bit dizzying. Apparently my eyes adjusted after a few minutes though because I only had the blurry experience once again, right after the break.
I thought the colours and resolution were crazy in a good way, but the 3D actually looked like it did in the 80s. The scenery shots looked as if someone had pushed different set pieces in front of one another, not natural at all. I know someone who watched it in 3D 48fps and then in 3D 24fps the next day and she said the 24fps-version looked a lot more natural.
The movie itself was underwhelming to me, to be honest. It was a nice movie to have watched once, but I don't have any desire to watch it again.