I haven't seen that much. The impression I have is it can be done well or badly, (like much else), not that it's intrinsically awesome or terrible.
I saw the last Harry Potter movie (pt. 2) both in 3-D and without, and I was actually really impressed by the 3-D version.
There were also a lot of 3-D previews when I saw it, and from that I can hazard that "Arthur Christmas" sucked despite 3-Dness (as per Jespah's comment), and "Hugo" looked very, very good.