Tom said it best. The rapping on GLEE is just so so so embarrassing, especially for Matthew Morrison (though I personally think he looks lame in the show whether he is singing a ballad with an ukulele or rapping or trying to deliver a joke).
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"