While Kung-Fu Panda and How to Train Your Dragon were DREAMWORKS movies and not Disney, looking at Bolt (Disney) or any of the Tinker Bell 3D movies (Disney) I have to agree that sometimes it's a mixed bag - uncanny valley or not. I find that fully animated features like How to Train Your Dragon and The Incredibles (Pixar) actually don't put people off as much as movies that try to intergrate CG characters in live action films. Usually with fully animated CG films, the focus is on how well the story grabs you and less about how well the characters achieve realism. Actually, in these films, realism for a character isn't about skin or even lighting but instead, do they hit the right beats of expression for the mood of the scene. That's why these tend to be better recieved, as more attention is given to facial animation, I find, than you see in films where CG characters are melded with live actors. Oddly enough, it is when CG characters are intergrated with living people that facial animation is the most important but often the most ignored.

 

For me, where films like Tron 2 (Disney) and the like go wrong is the facial expressions are too dead, as Slowhands pointed out. Dead in the mouth and eyes especially, and the skin is usually either too plastic or too translucent. I see lots of progress to getting beyond the problem but for now at least, full blown realistic humans are just tough to do in a two hour film since they get scrutinized more. That's why it's so jarring when you run accross a digital actor in those sort of films.

The only times a full CG feature bugs me is when lighting and animation fall short. Mouths and eyes are very expressive and in order to make a character - any character, even a human - believable, the eyes and mouths must animate with expression that carries over the face as a whole. A little exaggeration is often needed when using automated voice over apps (like Poser's own Talk Designer or XSI's Face Robot). As an animator, you will only get back what you put in, so if you don't check your frames for dead moments where you can overlay actions (eye wrinkling over smiling, eye widening when brows moved in anger, etc) you're going to make the character less appealing. It also helps to listen to the dialog as you're animating or read the script, so that your character's face can illustrate vocal changes in mood.