Wow what a crappy poster. What a shame that the art of the poster is all but gone now. When I look at the classic poster art from the early 1900's through to the 80's, I feel like crying to see how posters have now become a lousy cut-n-paste industry with absolutely no talent whatsoever. This poster is a perfect example.
I have seen a few really amazing conversions to be honest. I saw Piranha which was filmed with 3D conversion in mind from the start, and the conversion took close to a year, and it shows. I'm not sure I would have known it was converted if I hadn't already read it - it was that good.
A large part of Transformers 3 was actually converted, though some of it was shot in 3D, and it looked amazing - again I didn't know much of it was converted until I read about it after I saw it. And I saw Beauty and the Beast 3D which was incredible.
So given the right talent, a conversion can look amazing, though i naturally prefer films to be shot in 3D from the beginning. That said, this is Star Wars we're talking about here, and I'm sure it will look rather terrible if the poster and recent blu-rays are any indication.