Learning new things is good, but relying on any particular piece of technology being able to support you throughout your career is a recipe for failure. Be prepared to keep learning, and accept that quite a bit of the knowledge you have today will be useless ten years from now; they you should be fine.
ATG DAF is one of cool frameworks which has many advance features(component oriented dev,dependency injection, data anywhere architecture) . working with it would definitely will give a nice learning. Search for ATG in Oracle's website for more information.
if you are a developer with 0-2 years of exp and if your passion is on building applications with great flexibility and design, i think you should go for it.