Toy Story 3 isn't as good as the first two. It is more poignant than the first one though, and generally more emotional than the second, but as a work of craft, it falls behind. It's not as good because Lee Unkrich doesn't appear to be as good a director as John Lasseter, who directed the first two Toy Story films. In the same way that I found Up to be inferior to Wall-E or The Incredibles, the balance required to wedge lots of story into the comparatively short 90-minute "kid block" was slightly beyond him. Whereas Toy Story 1 and 2 had one primary journey and a great deal of exposition and character exploration at the key points, Toy Story 3 is much more rambling. They spend the entire movie running from place to place. I found it less focused and a less disciplined example of story blocking. This is, generally, unimportant. Taken as a whole, the movie is powerful, funny, sad, and above all, joyously entertaining.
The short before Toy Story is called Day & Night, which is Pixar's strongest short since For the Birds. It is an artistic take on a hand-drawn character awaking and representing day time. He meets another character who is asleep and represents night time. The two then begin a short adventure as they discover the joys and differences between night and day. Visually, it's just fantastic. And much like music videos, that's what makes shorts so cool. You don't need story coherency. It can be jumbled nonsense thrown on the screen for no other reason than visual wonder. This short is not jumbled nonsense, but it does take all the freedom allowed by a short and puts it to good use in the construction of something coherent and beautiful.
It reminded me a great deal of Chuck Jones' adventurous work in the late 50's and early 60's, like his now legendary Duck Amuck, but especially his hilarious (and personal favorite) Now Hear This: