Pixar started out by giving inanimate objects life, such as in the iconic short Luxo Jr. Now although robots are not exactly inanimate, an interesting decision was made to not give them human voices as is done in most other films using robot characters.
Although at first this seemed a bit odd, I (along with many other people) thought that if anyone could pull that off, it would be Pixar.
And pull it off they do. The characters a engaging, charming and far more captivating than those of Cars for instance.
It's still not up to the standards of Toy Story, but I thought it was a bloody good film.