I have mixed feelings about this. Is that a good thing? Should we now get back to writing Java UIs and then just compile them to javascript?
I use it daily at work. It's an impressive feat of engineering with a lackluster ecosystem and inconsistent documentation. Although it's not dead yet (at least technically) as it still has (slow) active development happening.
That said we're not using GWT for CSS, so that reduces iteration time where it's most noticable.