Not had any experience with ZDP-189 but from the specifications sounds like another top notch stainless steel for a knife. Similar in many respects to SGPS, another excellent stainless steel. The ZDP-189 sounds excellent, very hard with good edge retention but may have problems with corrosion and edge pitting.
http://www.cutleryscience.com/reviews/blade_materials.html#S_ZDP189A good resource for knife makers,
http://www.cutleryscience.com/reviews/blade_materials.html