Problem with Grönemeyer is - he is famous in Germany that almost nobody can understand what he sings.
No joke, it's true. Say "Grönemeyer" on the streets, and people immediately say "Boy I can't understand that guy..."
He should write songs, but not sing himself, imo. A few of his texts and songs were good, most do not interest me. In German pop music he is one of the leading big numbers. "Das Boot" was just an experiment in acting, he does not make any appearances as actor since then. In a long talkshow I once saw him in he gave me the impression to be a very reasonable, intelligent and sensible guy.