The various SOAP and WS-* related specifications have the reputation of being tricky and difficult to understand. The latest project I am involved in requires a relatively deep understanding of WS-*. One way to gain understanding of a specification is by closely studying an implementation of it. Spurred by my previous pleasant experience with it, XFire happens to be that implementation of choice.
Anyway, checking out the project from SVN and building from the sources was fairly easy. A number of tests failed, but all in all, it was a breeze to get the various XFire projects nicely tucked under Eclipse.
From what I can tell, the code is a pleasure to read and it feels like it is the result of fairly good design.