If the built-in reports didn't satisfy your reporting needs, then check out the "Report Store", a community to share report templates between end users. These report templates can be simply imported in few minutes into you existing OnCommand Report solution and get all the data immediately.
For how to import the report templates from the community to your OnCommand Report, look at the below link
Importing Custom Reports and Dashboard in OnCommand Report
Also look at this link on how to create your own custom report. Still not satisfied? post your needs on the community, we will try to design the report