In the OT, everything was tangible and rooted in the real world. It felt like you could really be there and touch everything. It had weight, it was used, slightly dirty and dinged-up. I really felt like there was a place I could go where I could stand on the decks of those starships. I could walk out in that desert and find a half-buried gaffi stick there. Even the models felt like they were really there, like they were solid and affected by gravitational pull somehow. And the cantina creatures, who were just guys with rubber masks on their heads... I related to them more because they were solid and humanoid. It all seemed like it existed, somewhere.
The prequels looked very real in most cases, but somehow just didn't have that weight or tangibility. Too many sets didn't exist behind the actors. Too many creatures were just high-tech cartoons. Somehow, that world was just hollow. And regardless of the skills of the actors, I could never be in touch with the scenery like I was with the OT.
CG should be used as a tool, not a crutch... and even then only to enhance and not to replace.
--SKot