I tried this out today with a Spring MVC + FreeMarker application. The support appears to be pretty primitive as my Spring macro library isn't recognized and most variables show up with warnings that they don't exist. Furthermore, there's no debugging support for setting breakpoints in templates (the JSP editor has this).
I hope this plugin gets much better in the future. For now, it just seems to provide syntax highlighting.
Are the Eclipse or NetBeans plugins any good?
Thanks,
Matt