For simple tasks jQuery is ok, for anything more than that I find it absolutely tedious (I usually pair with Underscore.js if I have to use it).
I also generally disagree with many of the design decisions in the jQuery API.
I think it's interesting that MooTools has been around for about the same amount of time, covers the same functionality, covers more functionality, and IMO better designed ...
I believe MooTools still makes extensions to built-in DOM classes, which other libraries avoid - even Prototype is moving away from that technique, and they were the first to popularise it.
I also generally disagree with many of the design decisions in the jQuery API.
I think it's interesting that MooTools has been around for about the same amount of time, covers the same functionality, covers more functionality, and IMO better designed ...
Yet it's not nearly as popular. C'est la vie.