Regarding Wicket itself: I really like this framework (we use it in my current team and it produces nice UIs that are pretty easy to maintain and change). Why do I like Wicket? Well for the following reasons:
- Its Java based, and since I'm strongest in Java it suites me.
- There is a nice separation between the UI in HTML/CSS/JS and the java code that backs it. This clear separation between the presentation/design aspect and the coding is useful because it separates along the common skill groups. JavaFX (can you say "designer/developer workflow") may change my opinion on this but right now I see advantages over say the JSP approach.
- Testing is well covered (with WicketTester) over and above just using something like Selenium (also mentioned in the book).
- The AJAX support seems solid and flexible. It even leaves you open to using other 3p JavaScript frameworks for your fancy UI components. In particular there is lots of support for request/response queues and falling back to full page refreshing that is particularly attractive.
BTW...I love manning books. The fact that you can get a free ebook when you purchase the print copy is excellent and in general everything I read from the publisher is superb.