The JS documentation for the new Grid component contains alot of classes and alot of inherited methods. For someone who is not very advanced with object-oriented development, it may seem complex or difficult to trace the various inherited methods through the class hierachy. It may also seem like the Grid is difficult to use. While most of the classes in the YAHOO.ext.grid package are designed to be plug and play, extended and customized, it still very easy to simply plug the grid into a webapp with a minimal amount of code.
More info: Home Page