Google always strives to make things Simpler to develop and Easier to use !
GWT benefited tremendously from the advancement of App Engine !
Its also blessed by SpringSource which directly integrates into APP Engine through the ground-breaking Spring ROO. So this means less steps to follow and less boiler-plate code to write! save time by avoiding infrastructure-setup
It was always simpler to create – say modular, reusable client-side cache, pagination table, model-ui binding API bypassing monolithic javascript libraries ! So easy it is to leverage Spring4GWT ‘servlet’-less server side coding and leverage Hibernate-validation !
Actually it saved months of work in couple of projects !
How about scalability and performance ? Its a good time to adopt Ext GWT ! – lightning-fast traversal of millions of records !
How to architect high-performance gwt –
Test the speed of GWT in Chrome –
Some of the links related to GWT.
Well ! GWT is for Java Geeks !  How’bout common masses who just owns diverse set of data – ranging from    – geographical info, traffic data, weather info, chemical properties, physics measurement data, population info – Hey we just want to visualize our data  – we hardly care about building an App !!
Here comes Google Fusion Table – it will load your data into Cloud (read Fusion Tables) and display/ report in Visualizer UI.