I actually liked CHAINSAW in 3D. It seemed a real sequel and not a remake. I also thought there were some marvelous 3D moments, like when the protagonist is in the back of a cab (I am not real clear where she was), but in any case, she was behind smeared plexiglass and the surface of the glass really added to the 3D-ness.
OZ was fun but after a while, a bit "meh".
I still highly recommend DRIVE ANGRY for the perfect combination of gutter-level exploitation elements, a kick-ass female character, and of course Nic Cage. Also, the 3D was fun and native.
Anyone here see THE THREE MUSKETEERS in 3D? I assume the 3D is good as it's directed by Paul W. S. Anderson, the guy who did the two RESIDENT EVIL 3D flicks. Lord knows how good the story is, of course.