I'm personaly fond of GWT, but I read on an IT magazine yesterday that according to Gartners, GWT (and also JFX) were only declared "promising"... Silverlight, Laszlo, and several JS libraries were "positive" technologies....
It is obviously only a comment from one the most known consulting cabinet...but it makes us thinking of the fundaments of our "faith" in such or such technology... In fine we never must be a "ialatollah" of a technology, but still continuing to look around us and choose a language, a framework, a libray, a pattern, ..., only according to the context in which we have to make a decision.
The equation is each time different, and unknown values/constants too.
Actually, why not Flex or AIR instead of GWT....according to the context?