While Java FX 1.2 can't live up to that promise just yet, it is nonetheless fun to use. The biggest missing component is a design tool. The FX community is abuzz with the possibility of this gap being bridged in the next version, hopefully to be released sometime soon. Some early screen-shots can be seen here.
On the plus side, Java FX (on the desktop) has access to the full class library of Java SE. Unfortunately, this isn't true for the browser or mobile versions (for obvious reasons.) For those configurations, we have to wait for the default Java FX class library to grow.
The following is a simple (and ugly - GUI design isn't my forte) Java FX application that graphs the yield slope over the last 30 years.
Click the image to run the program