While investigating GWT, I came across this comment.
I do not recommend GWT, because I had 1 year experience with that : List of GWT disadvantages: -simplest thing to be done requires 4-5 java classes with complex relationships -UI work fully concentrated in hands of very experienced java programmer, not simple -UI java programmer should also be aware of server side affairs very well, so hire 5 years experience programmer and GWT might become more friendly -not friendly for SEO -heavy dependence on Javascript, really it’s pure javascript, with all disadvantages of this insecure and problem-making technology -seems to create memory leaks in browsers -compilation time is very long -requires your custom effort to integrate ORM or data layer -there is no clear separation between work of web-master, server side java programmer and art-designer. It seems art and presentation layer workers should access java code with good confidence.
List of good things: -testing is quite simple
I recommend Jboss Seam as a much more mature and thoughtful solution, including several UI options.