> in that you've got your json manipulation, routing, connecting to a database, DI, actors,

While I agree with you about the others 'json manipulation' is not an area that Play can even be compared to Jersey (Jackson). Jersey transparently converts the request body to the required input type whereas with Play you still have to un-marshal the body while taking care of errors (admiddently that can be 'hidden' away using Action composition but still is work that the developer has to worry about). With Jersey its magic that just works.