The main difference is the addition of the Intelligent Lens Aperture, and how it makes the black levels look deeper in the darkest scenes, vs the RS55.
3D is significantly improved over my RS55 with less ghosting/crosstalk, for an over all sharper and more calm image. As Zombie has pointed out, while you can get a cleaner 3D image by adding a cheaper DLP
projector for 3D, the RS57's contrast advantage is noticeable in 3D as well. Realistic black levels and contrast combined with a good 3D title can be a really incredible combination for making the movie come alive.
Prometheus being one example.
I also like the new Clear Black processing (usually on Low) which adds some nice clarity.
And the Clear Motion Drive is much better.
The MPC processing seems similar, but because it's so much more elaborate in terms of adjusting it's settings, I still haven't figured out the best setting or exactly what might be different from my R55's MPC settings.
How important all these are will vary between users of course. In my blacked-out viewing environment, any deepening of black levels is welcome so it's significant to me.
Always enjoy reading your posts Rich! How do you feel about credits and the ILA? Livable? Pumping? Any other noticeable ILA artifacts while watching films?