The Z series lenses were good, but the bodies were horribly unreliable. IMHO, the ZM in particular was an aesthetically beautiful camera, but that funky wind lever/mechanism broke on nearly all of them, and don’t even get me started on the electronics.
If you’re interested in a later Mamiya, maybe looking into the compact N series, such as the NC1000, might be better? The lenses were pure Mamiya goodness and the bodies, while not rock solid, seem more reliable. It was the series before Mamiya jumped whole hog into electronic unreliability with the Z’s.