There is something about Struts that taps into the explanation centres of authors' brains and numbs them. I read 3 books on Struts before I "got it" and after I got it, I couldn't see why something so straightforward was so difficult to explain on paper.
Srikanth Shenoy & Nithin Mallya's "Struts Survival Guide" is the book that made me see though the clouds - you can find it on Amazon or you can download a PDF version from their website
ObjectSource for only $US10.99. Its pretty good and focuses on explaining how to do real things with Struts rather than writing a disseration on MVC patterns.
I also like the Manning Struts book in parts (eg. their taglib descriptions are very good), but you have to wade through a lot of not very well explained examples to get to find them.
Finally I think the names used for the Struts components are totally confusing for the beginner. Try leaving the word Action out and the meaning of things like ActionForms ActionError ActionForward becomes a little less confusing.