Do you recommend the integration with other frameworks? The two that I would like to know are: Struts and Spring
Or no, the integration doesn't worth all the problems that might result, and the developer should choose one of them?
From my experience I'd say Struts + JSF isn't worth it, pick one. The Spring + JSF should work just fine and have decent integration (though with CDI, what would you need Spring for, beside using it simply as a library?)