Spring roo is new framework and I found it very interesting. I have been working on web application for last 3-4 years and Always found JSPs are hard to maintain across teams if
Spring Roo 1.0.0 (GA) has now been released, complete with around 100 pages of documentation.
If you're wondering about what Roo is and why use it, I recommend you take a read of the introductory chapter of the reference guide. It covers this and more.
@Antony, GWT support is a major priority for Roo and something I am currently working on. Expect to see some interesting integration in the very near future.