I had the Burmester and had no complaints, would imagine the complaints are regarding standard audio. This applies to most manufacturers, the standard audio isn't very good.
2017 GLC AMG43 premium plus, night pack, leather, intel lights, 360 camera, side steps. = sadly gone
Now GLE450 Premium plus, Selenite, Black/White Nappa leather, Tech plus pack, Driving assistance pack, Tow pack, Off road pack, 22 inch wheels.