Hi Jack,
Apart from passing manufacturing/ ERP data back and forth, MII can also help to create business applications that help you for improving asset utilization and reducing downtime and so on. MII has many inbuilt frameworks which can help you here like Plant Information Catalog (PIC), KPI and Alerts etc.
In PIC you can maintain your asset hierarchy and also monitor the shop floor information.
More information about these can be found here:
Catalog Services - SAP Manufacturing Integration and Intelligence - SAP Library
Alerts and KPI - SAP Manufacturing Integration and Intelligence - SAP Library
MII provides you the basic platform for creating your own business applications based on your need. MII also provides you the framework to build these applications quickly by providing easy data integration etc.
Regards,
Rohit.