Based on a recent interview with the Java Posse, Oracle's making a pretty big bet on JSF and this component library -- even used in their Financials app -- so it's not as likely to disappear soon.
That said, I haven't used it -- still living with Struts 1.x -- so I can't comment intelligently on its real-world performance.
[Message sent by forum member 'djhagberg' (djhagberg)]