After a few months of using jQuery, I'm really pleased with how its working out. I get the feeling that it will only get better from here on out.
One of my favorite things about it is how the syntax for dealing with built-in functions as well as plug-ins is very consistent. That makes things much more feasible for many reasons.
At the moment, I'm feeling like the jQuery API is substantial enough to merit building applications around it rather than just using it to provide some ease-of-use on existing applications.