>Considering that the best language in the world (ahem) has about twice as much of ridiculous bugs or syntax weirdness, and it's still the best, I think JS is just great. And since it's open source, you easily find solutions to almost anything - see here.
>
>I specially love jQuery, and the way it operates on whole ad-hoc collections of objects. An equivalent on SetAll(property, value, ClassOrOtherAttribute).

The only very difficult, abstract matters with JavaScript are the concept of closure, variable scope and Function execution context. Once you have a little grasp on that, it's just an amazingly powerful language, very much underscored among 'classic' developers IMO.
As you point out, javaScript frameworks like jQuery hide those difficulties, most developers using a JS FrameWork don't even care about closures.

Browsers work very hard to compensate for JavaScript being an interpreted language (e.g. type inference in Mozilla FireFox 9), just like companies like Zend compensate for php being an interpreted language.

jQuery + underscore are quite equivalent to Prototype + Scriptaculous (created 1 or 2 years before). jQuery is easier to learn, better documented and a single place (web site) where you can find almost anything you want. I personnaly prefer Prototype's principle of extending native JavaScript objects; I find it easier to write and understand (probably because of my VFP experience <s>)
Both implement methods having the same signature as future native features (based on specs by ECMA or W3C), and call those features whenever available.