JavaFX seems cool but the deployment possibilities are weak:

• On the desktop computers that have an updated JRE can run JavaFX applet (but OpenJDK on Ubuntu 10.04 just dies)
• There doesn't seem to be any phone advertised as supporting JavaFX. The HTC Diamond that Sun was giving away at JavaONE 2009 was running Windows Mobile. Not exactly a market leader.

To be able to deploy on a lot of older hardware it seems safer to target the old J2ME and use a compatibility library to port the software to modern hardware (J2ME library)