Resig is spot-on regarding Objective-J

Resig:

Pyjamas, GWT, and Objective-J all hinge around a central concept: Abstracting away the authoring of JavaScript-heavy web applications by allowing the developer to program entirely in their natively language (be it Python, Java, or an Objective-C-like-language accordingly)…

I worry about large abstractions like this for a number of reasons.

Well worth the read.