As for the exhaust note, it is terrible.
What people are forgetting is that every single non-V8 ///M car ever built had a terrible exhaust note.
However, BMW often made up for that with great induction noise. The e46 M3 CSL exhaust sounds raspy and horrible, but the intake noise overshadows that by a long shot.
It is arguably the best induction noise I ever heard on a production car.