Java FX Tooling comes with lot of examples. I tried some (bounce, applets etc.), there were no problems at all.
Applets can be started in applet runner or browser - it just worked. You can choose between JavaScript or JNLP integration. Support for "draggable" applets is available as well. It didn't worked in my case - probably my JDK 1.6u10 plugin is too old.
Code completion is fast and works as expected.Preview works functionality worked in all cases.
The compilation process is well integrated in the build lifecycle. There is a non-visual drag and drop support available (similar to the non-visual JSP stuff). It is useful. You can just drag transformations, animations, Swing components etc. directly to your class.
Debugger works as expected, breakpoints etc. just work as in the Java case. Very useful to understand the existing code (in my case the bounce example).
The tooling is similar to the "old" Netbeans 6.0 based. However it is much faster and more stable.As a "technology preview" it is robust, fast and useful. And it came on time. They promised to release a preview in July at JavaONE - and it came in July (31) :-)