I remain unconvinced that 3-D represents the future of the movies, but it tells you something that Zemeckis' three 3-D features (also including "Beowulf") have wrestled from me 11 of a possible 12 stars.
I like the way that Zemeckis does it. He seems to have a more sure touch than many other directors, using 3-D instead of being used by it. If the foreground is occupied by close objects, they're usually looming inward, not out over our heads. Note the foreground wall-mounted bells that we look past when Scrooge, far below, enters his home; as one and then another slowly starts to move, it's a nice little touch.
I'm seeing this on Sunday .... in 3D of course!