I have to say that the animation in Bolt really took me by surprise as well. I thought the characters were given an almost infinite amount of detail. I had never watched a CG Dinsey film (skipped Meet the Robinsons and the chicken thing) and, in a foolish way, took for granted that Pixar simply ruled the world of CG animated films with regards to animation quality. I'm not going to lie, Bolt really caught me off guard with how good it looked.
Bolt did indeed look great. Part of it was the level of minute detail, which didn't quite match Pixar's efforts, but was certainly increased over Dreamworks films or the previous Disney CG entries. What really worked better for Bolt, and I think is what people often confuse for detail, is the special muted style of production design they came up with. When Lasseter took over Disney Animation he started digging in to the production of Bolt and actually got the to try to emulate the look of some of the traditionally animated Disney films. This meant making everything not only detailed, but more painterly. They actually developed a method by with the 3-dimensional background sets looked like the classic handpainted, watercolour backgrounds stretched back to the beginning of Disney feature animation in Snow White.
The number of hairs on the dog, by the way, is not detail. That kind of stuff is automatically animated by computer software, and as computers develop it is possible to have more hairs and such.
If you want to see the best detail in animated features the best examples are probably Cars and Ratatouille. In Cars, everything in the world is beautifully and uniquely designed. If you pay close attention you can even see that the bugs in the film are miniature VWs and they leave tiny car tracks on dusty windows. That level of fine detail is not found in Bolt, but the detail that is there is highly commendable. I remember being in awe by the levels of detail the Pixar animators are willing to go to back when I saw A Bug's Life in the theatre and noticed that near the end of the film, the pencil that Flick is sitting on has bite marks in it. What other company would think to add such a small detail? That kind of detail only increases budget and time, but it also adds to the immersive experience of a Pixar production whether you notice every detail or not.
Take a look at my favourite still from Cars:
I admit that Bolt is a beautiful looking film, but there is nothing in the film that matches the kind of detail (or frankly, beauty) that you'd find in Cars.