I took my oldest kid to see Nightmare Before Christmas 3D last night. She was too young to have seen the original in theaters when it first came out, and I was curious to see how well the movie was transitioned into 3D. My official verdict is, "WOW!" You have got to see this while it is still in theaters! When I think about the time they must have spent transitioning this movie into 3D it boggles my mind. My daughter kept reaching out to grab things- trying to catch Sally as she jumped from the tower, trying to catch falling snowflakes, etc.
They took what is arguably the best movie ever made, and went and made it even better. I haven't had so much fun in a movie theater since... well, since those college days at the Rocky Horror Picture Show, but that's another story.
And no, they did not change the soundtrack of the movie- in fact the only changes I noticed other than the rendering into 3D were subtle little things, like better looking snowflakes and new images added to the ending credits which did not diminish the film at all.