[natedub]

Us too. After a year, we're still really happy we went with Closure, but trying to convince most javascript developers outside our team to learn it has an uphill battle. The learning curve is rather steep, there are no tutorials besides Michael Bolin's (excellent) book, and the similarities to java turn some people off.

But once you get past all that, you have a powerful library with a good set tools for unit testing and a compiler that does dead code removal, function inlining, optional type checking through JSDoc annotations, etc. Its miles ahead of any pure-javascript solution because compilation is so tightly integrated into the whole development process. And yet you don't have to compile to run the code in development, so debugging is no harder than before.

That said, it's worth noting that the closure library is not a framework. You build your own application structure, models, etc, so it's definitely more work to get started.