In some SE scenes where CG replaced has replaced the X-Wing and Tie models, I felt it improved the scene dramatically (the Tie Fighters seem to benefit the most from CG), but in other scenes the artificial movement of CG models stand out more than the original model effects did...it all depends on the scene.
I still feel that some scenes in the OT look far more realistic with model effects vs CG in the PT, because they actually were using real materials and real movement vs artifical movement and design.