I've been using Codename One and it allows Linux developers to build native applications for mobile devices in Java while working fully in an open source stack. Very cool.

The main issues with FX are the same as those people have with ActionScript. The language is reasonable as a scripting language to tie things together but it feels very odd for most Java developers. Unlike action script you don't get the advantage of the amazing GUI tools Adobe offers.

Web start seems simple when creating hello world, NetBeans gets you started with a self signed JWS version. For production you will need a proper certificate which is harder but doable. Then there is the issue of pack.gz with its odd special case servlet (don't get me started on that one). Then you have the issues of HTTPs deployments not working for some people and the multiple incompatibilities between JWS versions installed which occur when someone has a corporate PC with a specific version of Java installed.
There are lots of issues some summed up here for older versions:
http://www.jroller.com/vprise/entry/should_you_use_jws

Newer versions of JWS (Java 6u10) broke different things but didn't really fix lots of the long standing issues. Most people using JWS just got burned one time too many.

Since no one is using or interested in FX what you are saying is far more unlikely.

FX has damaged Java's existing client side developers (yes there were many) by pulling funding from many important tasks such as the native look and feels which still don't work properly.

Its publicly despised by most Java developers who tried working with it and designers who compare it to Flash are just shocked that something as godawful as this would be released as a "Flash competitor".

Please actually try a technology before buying into the marketing nonsense that Sun has been spewing on FX. Our team did try this to produce demos and we were shocked at how horrible it was (I am talking production 1.0 and 1.1 versions!).

Another poster who never actually seriously tried FX!

We are serious Java and Flash experts and we spent a considerable amount of time with a direct line to the FX developers... Everything we were able to produce was just terrible.
Migrating skills from Java to FX is an exercise in futility, developers who had no Java experience had an advantage there. All us Java geeks were cursing the backwards way of doing things and the oddities, the IDE is ridiculous the live preview doesn't work and there is no way to visually build anything. Sure you can import really simple SVG graphics (not the elaborate stuff) but no animations and you need to start maintaining it in FX otherwise if node name changes well...

Communicating with the server, don't make me laugh! Did you try serializing an FX object to a server?
We were better off using plain Applets or even web start both of which now suck more because Sun spent so much energy on FX and botched the quality of Java 6u10.
Just read the Java developer forums where everyone is cursing FX. Other than Sun employee/contractors or people who didn't actually try FX no one is excited by this nonsense. Did you see the flashy demos, did you actually dig into the source code to see that most of them just use bitmap graphics for all the flashy animations???

Don't get me started on how ridiculous the mobile version of FX is.

You obviously never tried deploying a web start application. If it works then great its a wonderful thing, problem is that the simple idea is botched horribly on many machines due to multiple VM versions with incompatible web start revisions etc. There are some cases where you just can't figure out the problem. I defended and advocated JWS for years but Sun just can't get it right even with the huge investment for Java 6u10 JWS is still broken for many applications (not to mention breaking the native look and feel so badly that all sorted tables no longer work!).

BTW This is largely FX's fault which caused Sun to essentially move all non-fx development to maintenance mode.

Just finished the book too and loved it (same for both of his previous books). The book does say that you can succeed by your own merit but the *scale* of your success depends on your "history" or ancestry.
Personally my favorite part was the last chapter about Daisy which I found personal and very touching.