My sense is there is growing momentum behind GWT for people working in large teams. I've talked to a number of very talented developers that have worked on large scale projects that report big payoffs.

Unfortunately, there really don't seem to be any real alternatives or competition in this space.

It is somewhat surprising that Microsoft hasn't delivered any response. Silverlight is leading many companies down a road even Microsoft admits is a dead end for all but a few narrow applications.

We've been also using GWT for around 3 years now with great success for both inhouse and public facing applications. I'm surprised the author did not name the by far most compelling benefit: you can develop a huge codebase in Java, hence use your Eclipse, code completion, real time debugging, apply code metrics, Junit tests and you can share the same code on the client and the server (think domain objects, validators etc).

We've been USING GWT for our startup the past 2 years and have noticed huge performance gains. When you factor in bootstrapping, code-splitting, and the inhering advantages of using OO on a large code base the benefits are huge. SEo is a little tricky at first but with a few weekends of hacking you'll be getting indexed just as good as the rest of them. Happy hacking!