I haven't looked at this specific model myself, so I can't judge how good or complete it is. I do think a maturity model for BPM makes sense and could provide a valuable tool for understanding where the BPM gaps are within an organization.
An excerpt from the CIO Magazine Article
: "Many companies asked us how much business process management they should do and how well they conduct business process management right now," Rosemann says. "Our model lets them measure business process management along five factors. Those five factors are information technology, methodology, performance management, culture and accountability."