I can tell you about my not so long experience with JavaFX. After learning Swing, in my beginnings, JavaFX caught my attention and I learned it. My first impression was that it is a very powerful toolkit, quite customizable and with many widgets or controls. For example, you can display graphics without the need for libraries, pie charts, bar charts, etc. In the TableView you can easily customize the rendering to put images in cells, etc.
One of the features that I liked the most was the ability to use CSS directly on the controls, which allowed me to make very nice UIs, reminded me of GTK.
While it has come a little late (like Microsoft's WPF), it's a really good alternative to Swing and other toolkits. If you have some experience in Java, the learning curve will be very short.
About resources, you can follow this tutorial in Spanish, about the development of an agenda.