One thing that has always amazed me is how they were able to make the dinosaurs in Jurassic Park realistic. Looking through articles and PDFs, I came across the Dinosaur input device (now called Digital input device), or DID. Some notable differences between a stop-motion puppet and one that has the input devices is that:
1. The armature is 3 times larger in order to accommodate the servos and sensors.
2. No Ball and socket joints. All joints are hinges, swivels, and universal. The encoders can only sense a single axis.
3. Very precise (if built right).
4. The resulting animation lacks the artifacts of stop-motion animation, the pops and jerkiness, and yet retains the intentional subtleties and hard stops that computer animation often lacks.
Note: If you guys decide to comment on this post, please keep any CGI bashing you might have to a minimum.