I think the implementation can be much much better.
also there is a high need for more documentation. other that those 2 books already available.

I don't know what is wrong  in Seam but some times you have to restart your server to be able to undeploy your seam EAR application.

if I were in they place, I would write the core independent from JBoss specific components like hibernate, Drools and JBPM
and provide those features as extra abilities.
may be thats a good  commercial decision for them, but I don't like it.