I bet Disney is wishing it had bought out Pixar when it was still too small to object. :p I actually had no idea what PDI stood for before I read this; I had just figured PDI was always part of the Dreamworks tent...
The drawing doesn't make the movie--the plot makes the movie. It doesn't matter if it's done with hand-drawn animation or computers, if the plot fits and sits well, it will be successful.
I plan to see this within a week or two once my finals for this semester are over. Did it tie the two triologies together or did it leave a lot of unanswered questions between the third and fourth films?