The closure set of tools has been open sourced for a couple of years now and the last piece of the puzzle has landed, namely Closure Stylesheets. Now there is a full set of tools that are out there for you to use, not only that but the tools have been out long enough that there is help available.
Closure tools has been created fir a large team to create large applications. This has been the main hurdle to new developers wanting to learn. Most new developers will begin to learn closure at work in a team. Luckily there are now tools out there to help single programmers start for any size of project. Here is what you need to start:
Plovr is a tool written by Michael Bolin and makes using the library, compiler, templates and tests a breeze.
You probably use backbone.js or some other MVC. Well now closure tools has an MVC too, PlastronJS. If you read this blog you should know all about it by now. It's designed to be familiar but also, like the closure library, have many more features you can choose to call on or disregard depending on your needs.
An honorable mention should go towards the closure coffeescript fork which does a great job removing the "wordiness" of the library.
If you were about to go hop off and try Closure Tools for the first time I recommend waiting just a little bit more. Closure Tools now has a meetup which means the community is going to get stronger and the toolset is going to get easier. In fact I'll have another little project to announce very soon that should help you on your way. In the meantime I recommend starting by reading the book and keeping your eyes peeled on this blog for further announcements.