Well I think it's implicit that one of the things he thinks makes Shakespeare great is this engagement of 'poetry and patter' and he thinks Joyce also does this. It's not really an appeal to authority to say 'if you like Shakespeare, you'll this...'; and also implicit that the book is widely understood to be good, just difficult/inaccessible (but the digital age can solve that problem. Like, if ever there was a good time to read Ulysses, it's now).