I want to learn GWT. The problem ist that I have books for 1.5, 1.6, 1.7 version GWT and currently is 2.4 version. Is it useful when I read these books or the arhitecture has so changed that it makes no sense?
GWT is fast evolving, so the books might not be really up to date. My experience is that the official GWT site has a detailed developer guide which is extremely useful. I would suggest using the books as a reference point to get your basics straight, but also refer to the site for any enhancements and new features.