I've been working with Lift a bit. It is very different from any other web framework I've ever used. That said, there's some real brilliance in it, especially how Comet and Ajax work. Lately, it's gotten a lot easier to work with, as the IDE has gotten into a usable state.<p>The learning curve is pretty steep though. You have to learn Scala, The Java APIs and the non-traditional approach to web development that Lift takes. That, and it's a young ecosystem. There aren't 101 e-commerce shopping cart systems written in it yet.