I think they've nailed it. I have been ambivalent about GWT for a while, but couldn't quite put my finger on why (i.e., it's a "reasonable implementation of a poor architectural choice"). They've also very cogently argued why CoffeeScript doesn't fall into that category.
To paraphrase Thoughtworks's critique of GWT, jQuery is an elegant way of working with a horrible object model (the DOM). I don't know if there is any way to replace the DOM with a better client-side abstraction, but until then, the best of client-side goodness will remain somewhat unsatisfactory.
[Most people might go "BEEP who?", but in my opinion, this is a technology that was sadly delayed by over a decade, perhaps because of personality politics caused by creator Marshall Rose's less-than-smooth interactions with powerful members of standards bodies, who then blocked BEEP from becoming a standard until very recently. If we'd had BEEP 15 years ago, I suspect SOAP and WS-* would have looked very different, and perhaps REST would have looked different too. That's how powerful it is, and I still think it will change our lives one day.]
Well, so there's a piece of work to be done to enable TLS within the core of Nodejs, but that's not all.
So that's my current view in a nutshell:
* jQuery is great on the client side, but will no one rid me of this turbulent DOM?
* Nodejs is The One on the server side, but lacks some critical features (e.g., TLS and E4X). I don't know if they know about broken TLS, but they don't seem to think E4X even belongs in the to-do list, which is a pity if true. I'd like to be proved wrong.
* We need better server-side frameworks, and these are already on the way. We just need to wait till the dust settles to pick a winner.
I'll post updates as my view evolves.