Easy, simple and intuitive. Especially take a look at @InjectMocks and @Mock if You're Spring user.
There is one thing that renders this framework unusable - bugs. There is hundreds of registered bugs, but versions still get released with no fixes. They are not showstoppers but my team was able to find bugs in most of the major components. Some are JSF related (like ViewScope, which is useless for a full year now without a fix), some make you abandon the intuitive path for workarounds and hacks. Showcase may look good but a few months into development I am all for abandoning Richfaces and JSF in favour of anything else.
There's nothing good about richfaces - bugs in components, poor community support, overengineered components, old jQuery, skinning issues. Don't use.
After a 2 year journey with different versions of JSF I would never ever again use anything connected to this specification.
There are tons of bugs like this: http://java.net/jira/browse/JAVASERVERFACES_SPEC_PUBLIC-790 - Critical, open for longer than 2 years with no resolution. Framework is useless because of bugs and terribly low performance in comparison to anything else.
Unusable. Major bugs not fixed for more than a year. For example:
Too complicated and low performant for bigger traffic. Huge memory footprint, complicated integration with Spring and tons of other disadvantages
Help yourself, do not use.