Depends
On Alotta Things

^Agree....

All songs are different, and dont need 'punchlines' (unless a diss track) to 'show' lyrical abilities. i look for an Artist's Flow, Delivery & Clever Metaphor's.... And some clever metaphor's delivered with a nice Multi Scheme always makes my ear excited...

It depends mostly on who I'm listening to and what the song is about. If I'm listening to someone like Common or Mos Def, they don't need a punchline as long as their message is on point. If I'm listening to someone like Papoose or Cassidy rapping the usual bravado-filled "I'm the shit and no one can fuck with me" type of rap, I would be thoroughly disappointed if I didn't hear one good punchline.